BoilerFaultCodesAll Boiler Fault Codes
Every boiler fault code in our database — 5,449 codes across all UK manufacturers. Click any code to see which brands and models display it, with plain English explanations and fixes.
Most common fault codes
These appear on the largest number of boiler models across the UK market.
10 173 models 12 161 models 20 156 models 13 119 models 24 116 models 15 107 models F1 100 models 14 98 models 28 96 models 30 93 models 06 89 models 25 85 models S.53 84 models S.54 84 models 02 84 models S.20 83 models S.27 83 models S.30 83 models S.32 83 models S.34 83 models 05 83 models 23 82 models 29 81 models 31 80 models 18 78 models 16 78 models S.21 78 models S.23 78 models S.24 78 models S.28 78 models 40 76 models F.10 76 models 01 76 models 04 75 models S.31 74 models S.26 74 models 11 74 models 26 73 models S.11 73 models S.17 73 models S.04 72 models S.01 71 models S.10 71 models F.22 70 models S.16 70 models S.05 69 models S.07 68 models S.14 68 models S.96 68 models F4 68 models
0-9 (1708 codes)
_CL _St -. / Y -ll- .0 (B) LED turning on (D) LED turning on (G) LED turning on @6 (( \/r/e +8 +C +D +F >3.0 bar 00 000 0 (Flashing) 0 / A 0 / H 0 / Y 0 1. 0 2. 0 4 0 8 0 bar 0 nn 0-A1 0-A2 00:1 00:2 00:3 00:4 00:5 00:6 0.0 0.3 bar (flashing) 0.4bar 0.5 0.5 bar 0.5bar 0.6 bar 0.8bar 0.45 0.46 0.47 0.48 0.49 0.50 0.51 0.53 0.54 0.55 0.56 0.58 0.59 0.60 0.63 0.65 0.66 0.68 0.70 0.71 0.73 0.75 0.76 0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.95 0.97 0.99 0A 0A1 0A2 0A3 0A5 0A7 0A9 0A15 0A16 0A17 0A18 0A21 0A30 0A31 0A37 0A43 0A44 0A80 0C 0D 0E2 0E8 0E13 0E25 0E32 0E33 0E34 0E37 0E45 0E46 0E81 0E98 0E99 0F 0H 0L 0U 0Y 01 001 0001 1 - IGNITION FAILURE 1 0 1 1 0 3 1 0 4 1 0 5 1 0 6 1 0 7 1 0 8 1 01 1 1 0 1 1 6 1 1 8 1 02 1 2 3 4 1 03 1 04 1 05 1 06 1 07 1 08 1 8 1 09 1 9 1 10 1 14 1 16 1 18 1 bar 1 flash green 1 flash red 1 green flash 1 nn 1 P 1 1 P 2 1 P 3 1 P1 1 P2 1 P3 1 P4 1 red flash 1 second ON 1 second OFF 1 to 9 1 to 24 01 to 99 1-A1 1-A2 1-A3 1-A5 1-A6 1-A7 1-b2 1-b3 1-b4 1-b7 1-b8 1-C1 1-C2 1-C4 1-C6 1-d1 1-d2 1-d3 1-d4 1-d5 1-E1 1-E2 1-E3 1-E4 1-EA 1-Eb 1. 1. PILOT WILL NOT LIGHT 1.0 1.0.0 1.0.2 1.1 1.2 1.3 1.3.1 1.4 1.4.1 1.4.2 1.4.3 1.5 1.15 1.17 1.20 1.23 1.26 1.29 1.32 1.35 1.39 1.42 1.45 1.49 1.52 1.56 1.59 1.63 1.67 1.71 1.75 1.79 1.83 1.87 1.91 1.95 1.99 1.A 1.C 1.d 1.E 1.W1 1.W2 1.W3 1.W4 1=12 1A 1B 1C 01E 1F 1P4 1x 02 2 - CIRCULATION FAILURE 2 / F 2 / P 2 / U 2 0 5 2 01 2 02 2 03 2 04 2 05 2 07 2 08 2 8 2 9 2 09 2 AT 2 flashes 2 flashes green 2 flashes red 2 green flashes 2 lights flashing fast 2 nn 2 pulses 2 pulses (No light) 2 red flashes 2. 2.0 2.1 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.3 2.4 2.4.2 2.4.3 2.5 2.5 bar or above 2.6 2.7 2.7A 2.7bar 2.13 2.17 2.22 2.26 2.31 2.36 2.40 2.45 2.50 2.55 2.60 2.65 2.70 2.75 2.79 2.84 2.89 2.94 2.99 2.b 2.C 2/0/3 2/2/7 2/2/8 2/2/9 2/3/1 2/3/2 2/3/3 2/3/4 2/3/5 2/3/7 2/3/8 2/3/9 2/6/1 2/6/7 2/6/9 2/7/2 2/8/0 2A 2b 2C 02E 2E 2E:0 2F 2H 2L 2P 2S01 2S02 2U 2x 03 003 3 - OVERHEATING 3 + 3 0 1 3 0 2 3 0 3 3 0 4 3 0 5 3 0 7 3 0. 3 01 3 02 3 03 3 04 3 05 3 06 3 6. 3 07 3 7. 3 bar 3 flashes 3 flashes green 3 flashes red 3 green flashes 3 nn 3 P 9 3 P9 3 PILOT LIT, BUT NO MAINS GAS 3 red flashes 3.1 3.2 3.2.2 3.2.4 3.2.5 3.2.6 3.2.8 3.3 3.9 3.09 3.14 3.19 3.24 3.b 3.C 3.E 3.F 3/0/6 3A 03E 3P 3P9 3x 3Y 04 004 4 (Flashing Light) 4 (Flashing) 4 (Permanent Light) 4 / A 4 / C 4 / F 4 / L 4 / P 4 / U 4 / Y 4 0 4 1 1 4 1 2 4 1 3 4 03 4 04 4 05 4 06 4 07 4 08 4 09 4 17 4 24 4 26 4 30 4 31 4 32 4 33 4 AT 4 flashes 4 flashes green 4 flashes red 4 green flashes 4 nn 4 red flashes 4-5 4-A1 4-A2 4-A4 4-A5 4-A6 4-b1 4-b2 4-b3 4-b4 4-b5 4-b6 4-F1 4-F2 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.2.7 4.3 4.4 4.4.1 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4# 4A 4C 04E 004E 4E 4F 4L 4P 4U 4x 4Y 05 005 5 (Flashing Light) 5 (Flashing) 5 (Permanent Light) 5 / Y 5 + 5 0 1 5 0 2 5 01 5 02 5 03 5 04 5 28 5 29 5 61 5 65 5 Boiler Resets in 15 minutes 5 flashes 5 flashes green 5 flashes red 5 green flashes 5 nn 5 P 1 5 P 2 5 P 3 5 P1 5 P2 5 P3 5 P4 5 pulses 5 pulses (No light) 5 red 5 red flashes 5-A1 5-A2 5-A3 5.0 5.1 5.2 5.A 5.i 5.iv 5.v 5.vi 5.viii 5A 05E 5P5 5P6 5x 5Y 06 6 / C 6 / H 6 / L 6 1 0 6 1 2 6 04 6 05 6 07 6 09 6 10 6 12 6 flashes 6 flashes green 6 flashes red 6 green flashes 6 nn 6 P1 6 P2 6 red flashes 6-7 6-t1 6-t2 6-t3 6-t5 6-tA 6-tb 6.0 6.1 6.1.6 6.2 6.2.1 6.2.2 6.2.5 6.2.6 6.3 6.3.1 6.5 6.8 6.25 6.A 6.iv 6a 6C 06E 6H 6L 6P 6x 07 7 / A 7 01 7 02 7 03 7 04 7 05 7 06 7 07 7 8 7 9 7 11 7 12 7 13 7 22 7 23 7 50 7 flashes 7 nn 7-7 07, 09 7.0 7.1 7.2 7.2.1 7.2.2 7.3 7.3.1 7.4 7.4.1 7.4.2 7.5 7.5.1 7.i 7.iii 7.iv 7> 7A 7C 07E 7F 7H 7L 7x 08 008 8 (Flashing) 8 03 8 04 8 flashes 8 nn 8-9 8.0 8.1 8.2 8.2 Diagnostic LED Indicators 8.3 8.3 Faulting Finding Codes 8.4 8.4.1 8.4.2 8.5 8.6 8.7 8.8 8.10 8.11 8.12 8.13 8.79 8.C 8.d 8.E 8/0/0 8/0/2 8/0/3 8/0/6 8/0/8 8/0/9 8/1/0 8/1/1 8/1/5 8/1/6 8/2/1 8/2/2 8/2/3 8/2/4 8/2/5 8/2/6 8/2/7 8/2/8 8/8/8 8C 08E 8E 8L 8x 8Y 09 9 (Flashing) 9 (w/ flashing b) 9 12 9 25 9 25 blinking 9 flashes 9 nn 9-7 9-11 9.1 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.1.6 9.1.7 9.1.8 9.1.9 9.1.10 9.1.11 9.1.12 9.1.13 9.1.14 9.1.15 9.1.16 9.1.17 9.1.18 9.1.19 9.1.20 9.1.21 9.1.22 9.1.23 9.1.24 9.1.25 9.1.26 9.1.27 9.1.28 9.1.29 9.1.30 9.1.31 9.1.34 9.1.35 9.1.36 9.1.37 9.2 9.2.1 9.3 9.3.1 9.3.2 9.3.3 9.3.4 9.4 9.4.2 9.5 9.6 9.E 9.F 9/b 9+ 9A 9A 362 9B 9C 09E 9E 9F 9F855 9F856 9H 9L 9P 9U 9U 233 9x 10 010 10 bar 10-11 10-25 10.1 10.2 10.3 10.4 10.16 10.i 10.iii 10.iv 10E 11 0011 011 11:9 11.1 11.1 Error Codes - Auto Reset 11.2 Lockout Condition 11.7 11.8 11E 12 012 12.5 13 13/14 13E 14 14 kW 14.3 14.6 14.65 14E 15 15.2 15/26 15E 16 016 16 Per Sec 16.12 16.94 16E 17 017 17.0 17.6 17.58 17E 18 018 18.64 18E 19 19.0 20 20-21 20.0 20.33 20/21/22 20V DC 21 21:0 21E 22 22.0 22.8 22.D 22E 23 23:0 23.45 kW 23/31 23E 24 24 kW 24 V fuse blown 24.0kW 24.7 24CDi 24cxi 24E 24i 25 25 BF 25:0 25E 26 26.0 26/36 27 28 28CDi 28i 29 029 29.30 29E 30 030 30 40 30 40 50 30 40 50 60 30 40 50 60 70 30 40 50 60 70 80 30 BF 30 Flashing 30:0 30° neon flashing 30°C neon flashing 30c 30cxi 30e 31 31.05 31.5 31E 32 32:0 32/34 32/50 32/50kW 33 33.76 33.S 33/35 33V DC 34 34:0 35 35.S 36 36.0 36.5 36/46 37 38 38/33A 38cxi 39 40 40 - 50 - 60 - 70 - 80 40 Flashing 40° neon flashing 40°C neon flashing 40e 41 041 41.5 41E 42 42E 43 43 mm 44 44E 45 46 046 46.0 46/58 46E 47 047 48 49 50 50 - 60 - 70 - 80 50 60 50 Flashing 50-59 50:0 50/51/52 50/70 50/70kW 50° neon flashing 50°C neon flashing 50e 51 52 52.0 53 53/54/55/56 54 55 56 57 58 58:0 58/70 59 60 060 60 70 60 70 80 60 Flashing 60/61 60° neon flashing 60°C neon flashing 60e 61 62 63 64 64.0 65 66 67 68 69 70 70 80 70 Flashing 70.0 70/72/74 70/90 70° neon flashing 70°C neon flashing 71 71:2 71/73 72 73 74 75 75 mm 75/76 76 77 78 79 80 80 B 80 Flashing 80-83 80:0 80/90/91 80° neon flashing 80°C neon flashing 80e 81 82 83 84 85 86 87 88 88 88 88°C flashing 89 90 90 Flashing 91 92 93 93/95 94 95 96 97 98 99 100 100 B 100FF 100mm 101 102 103 104 104H 105 105e 105H 106 107 108 109 109 R 110 110 R 110E 111 111 R 112 113 114 115 116 117 118 119 120 120FF 121 122 123 124 125 125 R 126 127 128 129 130 131 132 133 133 R 134 135 138 139 140 142 143 146 150 151 151 R 152 153 154 155 157 158 160 160 R 161 162 163 164 164 225 164 229 164 261 164 282 164-026 166 169 169-033 169-083 169-127 169-141 170 170W 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 193 195 196 198 200 200 mm 200 O 201 201 O 202 202 O 203 203 0 204 204 O 205 207 207 / CE 208 208 0 209 210 210 / E9 211 212 213 213 / D4 214 214 / C7 215 215 / C6 216 216 / C6 217 217 / C7 218 218 / E5 219 219 / E9 220 220 / E9 221 221 / E9 222 222 / E2 223 223 / E2 224 224 / E9 224 V 225 226 227 227 / EA 227 V 228 228 / F7 228 V 229 229 / EA 230 230 / EA 230V AC 231 231 / FD 232 232 / D3 233 233 / 9U 234 234 / EA 235 237 237 / C4 238 238 / F0 239 239 / F0 240 240 / D1 241 241 / D1 242 243 244 245 246 247 249 250 251 252 253 254 256 257 257 / b7 258 259 260 261 261 EA 262 263 264 264 C1 265 266 266 CE 267 267 F0 268 269 269 EA 270 271 271 D4 272 272 F0 273 273 C4 274 275 276 276 E9 277 277 E9 278 278 F0 279 279 F0 280 280 F0 281 281 A1 282 282 H5 283 284 285 285 E9 286 286 D1 287 287 F0 288 288 CF 289 289 CF 290 290 F0 291 292 294 299 299-357 299-360 299-363 299-495 299-506 300 300 mm 302 303 304 305 305 0 306 306 FA 306 V 307 308 308 557 309 310 311 312 313 314 315 316 316 E9 317 317 A3 318 318 E9 319 494 320 321 322 323 323 A8 324 324-822 325 326 327 328 329 329 CE 330 331 332 332 E5 333 335 336 337 338 338 F0 339 340 341 341 D4 342 342 D4 343 343 ED 344 344 ED 345 345 EF 346 346 EC 347 347 E3 348 348 EE 349 349 EF 350 350 E2 351 352 353 354 355 356 357 358 359 360 360 V 361 362 363 364 364 FA 365 365 Fb 366 367 369 370 371 372 373 373 8C 374 374 8C 375 375 697 375 699 375 E4 376 376 E4 377 378 379 380 381 381 656 382 383 598 384 385 386 386 575 387 388 391 392 393 395 396 397 398 051 398 055 399 400 401 402 403 404 405 406 407 408 410 416 417 418 419 420 422 423 424 425 426 427 429 430 431 432 433 436 437 438 446 447 448 449 450 451 452 453 454 455 456 457 460 463 464 467 468 471 474 489 490 499 501 502 506 516 517 522 527 528 540 544 545 547 550 551 591 594 599 600 600 mm 602 604 612 614 615 669 0714 727 728 729 738 740 760 762 782 800 800 CC 808 808 A7 809 810 811 812 813 814 815 828 0828 855 856 0870 900 918 931 975 980 1000 1010 1010 O 1013 1014 1017 1017 W 1018 1019 1021 1021 B 1022 1022 B 1023 1023 R 1025 1027 1037 1037 W 1065 1065 B 1068 1068 W 1070 1071 1072 1073 1073 W 1074 1074 W 1075 1075 W 1076 1076 W 1200 mm 1277 1476 1500 mm 1621 1780 1827 2040 2051 2085 2085 V 2126 2128 2130 2131 2132 2133 2169 2270 2419 2508 2526 2908 2908 V 2909 2910 2910 V 2911 2911 V 2912 2912 V 2913 2914 2915 2915 V 2916 2916 V 2917 2917 V 2918 2920 2920 V 2921 2922 2923 2923 V 2924 2924 V 2925 2925 V 2926 2926 V 2927 2927 B 2928 2930 2930 V 2931 2932 2940 2940 V 2941 2941 B 2942 2943 2945 2945 V 2946 2946 V 2947 2947 R 2948 2948 B 2949 2949 B 2950 2950 B 2951 2951 V 2952 2952 V 2953 2953 B 2954 2954 B 2955 2955 B 2956 2956 O 2957 2957 V 2958 2958 V 2959 2959 B 2960 2960 B 2961 2961 V 2962 2962 V 2963 2963 B 2964 2964 B 2965 2965 B 2966 2966 B 2967 2967 B 2968 2969 2970 2970 B 2971 2971 B 2972 2972 V 2973 2974 2980 2981 3071 3306 3657 4250 4254 4931 5298 5317 5351 5356 5406 5911 5980 5982 5984 6025 6800 to 6819 6901 7070 7618 7777 8036 8037 8176 8277 8301 8360 8367 8478 8484 8809 9266 9763 9764 9797 55427 布 & 皿 neons flashing 閃 neon illuminated
A (380 codes)
A A (number) A 0 1 A 0 2 A 0 3 A 0 4 A 01 A 1 6 A 02 A 03 A 04 A 05 A 07 (*) A 08 A 09 A 10 A 13 A 14 A 15 A 16 A 17 A 32 A 33 A 34 A 36 A 37 A 39 A 40 A 41 A 77 A CO A DJ A fault on gas supply A Flashing A Illuminated continuously A neon flashing A nn A short pulse every 4 seconds A-4 A-A5 A-b2 A-b4 A.(1) A.(3) A.00 .28 A.00 .29 A.00.34 A.02 .37 A.02 .45 A.02 .46 A.02 .48 A.02 .49 A.02 .54 A.02 .76 A.02.06 A.02.18 A.02.36 A.02.55 A.11 A.12 A.18 A.19 A.20 A.21 a/1/1 a/1/2 a/1/8 a/2/1 a/2/2 a/3/2 A0 A00.00 A00.34 A00.42 A1 A01 A1 281 A1.2 A1.3 A01.23 A02 A2 A2:0 A2.2 A02.06 A02.36 A02.37 A02.45 A02.46 A02.48 A02.49 A02.55 A02.69 A02.76 A03 A3 A3.2 A04 A4 A5 A05 A06 A6 A7 A07 A7 808 A8 A08 A8 361 A08.02 A09 A9 A09-12 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23 A23 - A24 - A26 A24 A26 A30 A33 A36 A37 A39 A40 A41 A42 A44 A47 A51 A54 A55 A56 A58 A59 A60 A61 A62 A63 A64 A68 A70 A77 A80 A88 A90 A91 A97 A98 A99 AA0011 AA0022 AA0033 AA0077 AA1199 AA2200 AA2211 AA2222 AA3333 AA9999 AC ACF electronic fault alarms ACO Activate Activate BCC Ad ADC LOCKOUT Adj AE AF AF1 AF2 AIR FLOW DEVICE Air flow fault Air Flow Monitor Air Flow Monitor Neon Air flow rate safety device AIR PRESSURE ERROR Air Pressure neon Air Pressure O.K. AIR PRESSURE OK Air pressure switch Air Proving LOCKOUT AL AL 00 AL 01 AL 02 AL 03 AL 04 AL 05 AL 06 AL 07 AL 08 AL 09 AL 10 AL 11 AL 12 AL 13 AL 14 AL 15 AL 16 AL 17 AL 18 AL 28 AL 30 AL 37 AL 40 AL 41 AL 42 AL 43 AL 44 AL 56 AL 57 AL 62 AL 72 AL 74 AL 77 AL 78 AL 79 AL 80 AL 81 AL 82 AL 83 AL 84 AL 88 AL 89 AL 90 AL 92 AL 93 AL 95 AL 96 AL 98 AL 99 AL10 AL20 AL21 AL26 AL28 AL34 AL40 AL41 AL52 AL55 AL60 AL71 AL73 AL74 AL79 Alarm ALARM 01 ALARM 02 ALARM 03 ALARM 04 ALARM 05 ALARM 06 ALARM 07 Alarm high limit thermostat Alarm system water pressure Alert ALL 02 ALL 03 ALL 04 ALL 05 ALL 06 ALL 07 ALL 08 ALL 09 ALL 10 ALL 11 ALL 12 ALL 13 ALL 14 ALL 15 ALL 18 ALL 20 ALL 21 ALL 22 ALL 23 ALL 24 ALL 25 ALL 26 ALL 27 ALL 28 ALL 29 ALL 30 ALL 31 ALL 32 ALL 33 ALL 34 ALL 35 ALL 37 ALL 40 ALL 41 ALL 42 ALL 43 ALL 44 ALL 62 ALL 72 ALL 77 ALL 78 ALL 79 ALL 80 ALL 81 ALL 82 ALL 83 ALL 84 ALL 88 ALL 89 ALL 90 ALL 91 ALL 92 ALL 93 ALL 95 ALL 96 ALL 98 ALL 99 All Lamps OFF All Lamps ON All LEDs Off All lights: OFF All neons flashing All operation lights OFF ALL01 ALL02 ALL03 ALL04 ALL05 ALL07 ALL08 ALL09 ALL10 Alternating flashing AM001 AM010 AM011 AM012 AM014 AM015 AM016 AM018 AM019 AM024 AM027 AM036 AM037 AM040 AM091 AM101 Amber LED illuminated Amber neon Amber neon (on panel) Amber neon lit An An 11 Anti-cycle ANTI-CYCLE DEVICE Anti-frost device anticycle AP AP073 AP079 APPLIANCE FIRES THEN LOCKOUTS APS Cycling LOCKOUT APS fault APS neon lit APS Stuck Fault ASE Autofrostat Function Automatic Shutdown
B (159 codes)
B b 18 b 19 b 24 b 25 b 26 b 28 b 29 b 30 b 33 b 38 b 61 b 65 B Flashing B Illuminated continuously B neon flashing B-2 B, C, D, E & F neons flashing B(5) b/E 18 b0 B1 B01 b2 B02 b3 B03 b4 b5 B05 b6 B06 b7 B07 b7 257 b8 B08 b18 b19 b24 b25 b26 b28 b29 b30 b52 b65 bA Bar Bar LED Flashing Bat bb.. BC BCC Activation Fault BCC error BCC Fault bd BE Below Minimum bF BLANK DISPLAY BLANK DISPLAY SCREEN Blinking RED BLOCK Block 01 Block 11 Block 12 Block 60 Block 67 Block 80 Block 81 Block 82 Block 85 Block 86 Blockage Blocked condensate pipework Blocked Flue/Condensate Blocking Blocking Error Blue indicator (2) will flash Blue indicator light flashing Blue indicator light off Blue light Blue light on Blue light: Off / Lockout: Off Blue light: On / Lockout: Off BM000 Boiler at lock out Boiler lock out Boiler lockout Boiler On Boiler ON (green) light off Boiler On (Orange LED) Boiler On light on Boiler On neon BOILER OVERHEAT STAT TRIPPED Boiler Overheat Thermostat Boiler Safety Overheat neon Boiler sensor BOILER SHUTDOWN Boiler sooting Boiler stand-by Boiler Temperature Boiler Type Card Fault Boiler Type Card Fault - Contact Installer Boilers Boiling Bottom red light bP BUBNEB STAYS ON BURNER (FLASHING) Burner air ports blocked Burner control box lockout light lit Burner fails to ignite Burner fails to light BURNER FAILS TO START BURNER FIRING 100% Burner goes out Burner indicator Flashing BURNER indicator Slow flash Burner LED Green Burner Lit Burner Lit LED BURNER LIT NEON Burner lock out indicator Burner lock out neon Burner lock-out Burner lockout Burner motor fails to operate Burner Neon (Flashing) Burner On Burner On (Green Light) Burner On (Green) light flash Burner On (Green) light on Burner ON LED (Green) Burner On light off Burner On Neon Burner ON neon (green) Burner On neon / Gas Valve On Burner On neon going out Burner on neon NOT illuminated Burner On neon off Burner output modulates BURNER panel LED flashing fast (2/sec) Burner reset light green/red alternate flash (0.5s) Burner reset light green/red fast flash (0.2s) Burner reset light orange steady Burner reset light orange/green alternate flash (0.5s) Burner reset light orange/green fast flash (0.2s) Burner reset light red fast flash (0.2s) Burner reset light red flash (0.5s on, 2.5s off) Burner reset light red flash (0.5s) Burner reset light red steady Burner reset light red/green inverted flash (2.5s on, 0.5s off) Burner reset light red/orange inverted flash (2.5s on, 0.5s off) Burner shut-down BURNER Slow flash BURNER STAYS ON BUS 485
C (139 codes)
C (Flashing) c 0 c 1 05 c 2 C 12 C 20 C 24 C 28 C 32 C 40 c 55 C 61 C 78 C neon flashing C.h. operation c/a/ C/H Sensor Fault c/u/ C0 C1 C1 05 C1 10 C1 11 c1 17 c1 18 C1 29 C1 33 C1 51 c1 54 C1 264 C2 C3 C4 C4 237 C4 273 C5 C6 C6 215 C6 216 C7 C7 214 C7 217 C8 C12 C13 C20 C32 C33 C40 C42 C52 C53 c80 C123 C551A CA Case sensor Case temperature Casting Thermistor Fault CC 800 CC.. Cd CD10 CD11 CE Central Heating LED flashing CF CFG CFL40 CFL50 CFL60 CFL70 CFL80 CFL90 CFL100 CFS CH CH 80 CH flow NTC sensor defective. CH LED CH light flashing CH light On CH light On (flashing) CH light on PCB 40 flashing CH PUMP Fast flash CH PUMP indicator Fast flash CH PUMP indicator Slow flash CH PUMP panel LED flashing fast (2/sec) CH PUMP Slow flash Check JP1 Circulation Circulation LOCKOUT CM030 CM120 CM190 CM210 CM280 CN12 CO COdE Code plug not detected. code9 COM COM1 Combi panel 2 flashing green Sensor LEDs Combi panel red Lockout LED Combi panel yellow High Limit LED COMBUSTION FAN FAULT Combustion lockout COMP Complaints of noise Complaints of noise (1) Compressor Stall Error Compressor Start Error con Condensate Drain Blockage Condensate in boiler CONDENSATE PUMP Condensate Pump (Green Light) Condensate pump failed condense pressure switch CONDITION 1 CONDITION 2 CONDITION 3 Connection Constant RED Control failed Control Satisfied cP CP000 CP020 CP210 CP230 CP470 CP480 CP490 CP780 CRC error Cylinder Thermistor Fault
D (275 codes)
d / U D neon flashing d.00 D.0 D.000 d.01 D.1 D.001 d.02 D.2 D.002 d.3 d.03 D.003 d.04 D.004 D.4 d.05 D.5 D.005 d.06 d.6 D.006 d.07 D.7 D.007 d.08 D.8 D.008 d.09 D.009 D.9 d.10 D.010 d.11 D.011 D.012 D.12 D.13 D.013 D.14 D.014 D.15 D.015 d.16 D.016 D.17 D.017 D.18 D.018 d.19 D.019 D.20 D.020 d.21 D.021 D.22 D.022 d.23 D.023 D.24 d.25 D.025 D.026 D.26 D.27 D.027 D.28 D.028 D.029 d.30 d.31 D.031 d.33 D.033 d.34 D.034 d.35 D.035 d.36 D.036 d.37 d.39 D.039 d.40 D.040 d.41 D.041 d.43 D.043 D.44 D.044 d.45 D.045 d.46 D.046 D.47 D.047 d.50 D.050 D.51 D.051 D.052 d.58 D.058 d.60 D.060 d.61 D.061 d.62 D.062 d.64 D.064 d.65 D.065 d.66 D.066 d.67 D.067 d.68 D.068 d.69 D.069 d.70 D.070 d.71 D.071 d.72 D.072 d.73 D.073 D.074 d.75 D.075 d.76 D.076 D.77 D.077 D.078 D.78 d.79 d.80 D.080 d.81 D.081 d.82 D.082 d.83 D.083 D.84 D.084 d.85 D.085 d.88 D.088 D.90 D.090 D.91 D.091 d.92 D.092 D.93 D.093 d.94 D.094 d.95 D.095 D.96 D.096 D.97 D.098 D.98 d.99 D.118 D.124 D.125 D.128 D.129 D.145 D.146 D.147 d.149 D.156 D.157 D.158 D.159 D.160 D.161 D.162 D.163 D.164 D.166 D.167 D.170 D.171 D.172 D.173 D.174 D.175 D.182 D.185 D.186 D.187 d.191 d.192 D.h.w. operation d0 d1 D1 240 d2 D3 D4 D4 271 D4 341 D5 D6 d7 d8 d9 d10 d11 d12 d13 d14 d15 d16 d17 d18 d19 d20 d21 d22 dA db dd.. dE Demand DEMAND NEON Detection Fault DETECTION LOCKOUT DHW DHW FLOW SWITCH DHW light DHW NTC fault DHW pre-heat function DHW PUMP (FLASHING) DHW PUMP Fast flash DHW PUMP indicator Fast flash DHW PUMP indicator FLASHING DHW PUMP indicator Slow flash DHW PUMP panel LED flashing fast (2/sec) DHW PUMP panel LED flashing slow (1 per 2s) DHW PUMP Slow flash DHW SENSOR LOCKOUT DHW thermistor fault DHWsensor Display Flashing Display not illuminated DM001 DM002 DM005 DM009 DM019 DM029 Does main burner light? (NO) Does pilot light? (NO) Double flash Blue light dP DP430 DP440 DRIFT TEST WAITING Dry fire sensor Dry-Fire DT dU
E (628 codes)
E 00 E 01 E 02 E 03 E 04 E 05 E 06 E 07 E 08 E 09 E 10 E 11 E 12 E 13 E 14 E 15 E 16 E 17 E 18 E 19 E 20 E 21 E 22 E 23 E 24 E 25 E 28 E 29 E 30 E 31 E 32 E 33 E 35 E 36 E 37 E 38 E 41 E 42 E 44 E 51 E 60 E 61 E 65 E 72 E 80 E 81 E 82 E 87 E 88 E 91 E 94 E 95 E 98 E 99 E neon flashing E:04.00 E.00.04 E.00.05 E.00.16 E.00.17 E.00.20 E.00.21 E.01.04 E.01.12 E.01.17 E.01.20 E.02 .13 E.02 .35 E.02 .39 E.02 .47 E.02.15 E.02.17 E.04 .29 E.04 .54 E.04 .254 E.04.01 E.04.02 E.04.03 E.04.08 E.04.10 E.04.11 E.04.12 E.04.13 E.04.15 E.04.17 E.04.18 E.04.23 E.04.24 E.782 e/\/ e/l/ E00 E0 E00 to E99 E00-684 E00-688 E00-711 E00-716 E00-720 E00-721 E00-722 E00-730 E00-737 E00-738 E00-741 E00.00 E00.04 E00.05 E00.06 E00.07 E00.16 E00.17 E01 E1 E001 E01 074 E01 075 E01 412 E01 530 E01 540 E01 553 E01---204 E01---205 E01-058 E01-059 E01-156 E01-372 E01-374 E01-490 E01-505 E01-507 E01-579 E01-580 E01-591 E01-596 E01-598 E01-599 E01-600 E01-601 E01-602 E01-603 E01-604 E01-605 E01-606 E01-607 E01-610 E01-612 E01-840 E01-886 E01-892 E01-893 E01-900 E01-930 E01-940 E01-941 E01-942 E01-943 E01-944 E01-945 E01-946 E01.04 E01.11 E01.12 E01.24 E2 E02 E02 026 E02 071 E02 078 E2 222 E2 223 E2 350 E2 351 E02-234 E02-313 E02-325 E02-347 E02-348 E02-349 E02-350 E02-365 E02-367 E02-372 E02-376 E02-379 E02-380 E02.13 E02.15 E02.17 E02.35 E02.47 E03 E3 E003 E03 818 E03-826 E03-827 E03-884 E03-885 E03-886 E03-887 E03-888 E03-893 E03-894 E04 E4 E004 E04-582 E04.00 E04.01 E04.02 E04.03 E04.07 E04.10 E04.12 E04.13 E04.17 E04.23 E5 E05 E5 218 E05-341 E06 E6 E06 058 E06 059 E06 060 E06 085 E06 097 E07 E7 E08 E8 E9 E09 + E9 219 E9 224 E9 276 E010 E10 E11 E011 E12 E012 E12 to E22 E13 E013 E13/16/19 E14 E014 E15 E015 E16 E016 E17 E18 E19 E20 E020 E21 E021 E22 E022 E23 E023 E24 E024 E24 077 E25 E25 425 E26 E26 186 E26 219 E26 221 E27 E28 E29 E030 E30 E31 E031 E32 E032 E33 E033 E34 E034 E35 E035 E36 E036 E37 E037 E38 E038 E039 E39 E040 E40 E041 E41 E042 E42 E43 E44 E45 E46 E046 E047 E47 E48 E50 E050 E051 E052 E52 E54 E055 E056 E56 E57-048 E57-049 E058 E58 E060 E60 E61 468 E61 483 E61 485 E61 490 E61 520 E61 547 E61 565 E61 567 E61 569 E61 665 E61 667 E62 E64 E065 E65 E66 E067 E67 E68 E69 + E69-243 E070 E70 E071 E72 E072 E72-401 E73 E73-355 E74 E075 E75 E76 E077 E77 E78 E78-180 E78-181 E78-210 E78-212 E78-236 E78-250 E78-367 E78-369 E79 E080 E80 E80-450 E80-451 E081 E082 E82 E82-317 E83 E83 458 E83 462 E83 465 E83 466 E83 467 E83 468 E83 476 E83 477 E83 481 E83 482 E83 483 E83 484 E83 485 E83 486 E83 488 E83 489 E83 491 E83---121 E83---129 E83---178 E83---180 E83---181 E83---196 E83---197 E83-013 E83-081 E83-082 E83-086 E83-101 E83-122 E83-126 E83-127 E83-142 E83-145 E084 E84 E085 E85 739 E85 740 E85 752 E85 753 E85 761 E85 762 E85 802 E85 901 E086 E088 E89 E090 E90 E90-627 E091 E91 E092 E92 E093 E93 E094 E94 E095 E95 E096 E96 E097 E97 E098 E98 E99 E099 E109 E110 E118 E119 E125 E127 E128 E130 E131 E133 E155 E158 E160 E193 E205 E218 E278 E279 E291 E302 E351 E352 E353 E407 E421 E434 E439 E441 E445 E480 E515 E517 E593 E594 E598 E615 E736 E740 E761 E762 E773 E777 E782 E783 E784 E786 E787 E788 E792 EA EA 227 EA 229 EA 261 Eb EC ECO ECO-button flashes ECO-button lit ECO-button not lit ED EE0011 EE0033 EE0044 EE0055 EE0088 EE2200 EE2211 EE2222 EE2233 EE5566 EE6644 EE6666 EE7744 EE9999 eeprom EEPROM LOCKOUT EF EF 349 EH 258 EL Electrical Fault Finding Electrical Supply Failure Electrical Supply Fault En Enn Er ER + 69 Er 01 Er 02 Er 03 Er 04 Er 05 Er 06 Er 07 Er 08 Er 09 ER 18 Er 19 ER 20 Er 25 Er 99 Er.1 Er.2 Er.3 Er.4 Er.5 Er.6 Er.7 Er.8 Er.9 Er.10 Er.11 Er.12 Er.13 Er.14 Er.15 Er.16 Er.17 Er01 Er02 Er03 Er04 Er05 Er06 Er07 Er08 Er09 Er10 Er11 Er14 Er15 Er16 Er17 Er17+RESET Er18 Er99 Err Err / 108 Err HJ-09 Err.5 Err.L Err.L - Err.5 Erroneous APS signal ERROR Error 00 Error 01 Error 02 Error 03 Error 04 Error 05 Error 12 Error 18 Error 19 Error 20 Error 28 Error 69 Error 80 Error 110 Error 119 Error 125 Error 130 Error 133 Error 160 ERROR CODE 1 ERROR CODE 2 ERROR CODE 3 ERROR CODE 4 ERROR CODE 5 ERROR CODE 6 ERROR CODE 7 ERROR CODE 8 Error in power supply Escape of Gas Et Excessively noisy burner Excessively noisy burner (1) EXHAUST SENSOR FAULT Explosion at burner Explosive ignition
F (702 codes)
F (Flashing) F 0 5 F 0 6 F 0 7 F 0 8 F 0 9 F 0A F 0C F 0d F 0t F 0U F 1 0 F 1 1 F 1 2 F 1 3 F 1 4 F 1 7 F 1 9 F 02 or FN or LN F 04 F 4 L 4 F 04 or L 04 F 05 F 5 L 5 F 05 or L 05 F 06 F 07 F 09 F 9 L 9 F 16 F A F H F L F P F U F.00 F.0 F.000 F.01 F.1 F.001 F.02 F.002 F.2 F.03 F.003 F.3 F.4 F.5 F.6 F.7 F.8 F.9 F.10 F.010 F.11 F.011 F.12 F.012 F.13 F.013 F.14 F.15 F.17 F.19 F.20 F.020 F.22 F.022 F.23 F.023 F.24 F.024 F.25 F.025 F.26 F.27 F.027 F.28 F.028 F.29 F.029 F.30 F.32 F.032 F.33 F.035 F.35 F.37 F.040 F.41 F.42 F.042 F.43 F.044 F.46 F.047 F.49 F.049 F.50 F.52 F.53 F.54 F.55 F.56 F.57 F.057 F.58 F.59 F.60 F.61 F.061 F.62 F.062 F.63 F.063 F.64 F.064 F.65 F.065 F.66 F.67 F.067 F.68 F.068 F.69 F.70 F.070 F.71 F.071 F.72 F.072 F.73 F.74 F.074 F.75 F.075 F.76 F.076 F.77 F.077 F.78 F.078 F.80 F.080 F.081 F.81 F.82 F.83 F.083 F.84 F.084 F.85 F.085 F.86 F.87 F.087 F.88 F.088 F.89 F.089 F.090 F.90 F.91 F.92 F.092 F.93 F.94 F.095 F.096 F.97 F.097 F.100 F.104 F.105 F.142 F.160 F.161 F.162 F.163 F.180 F.182 F.183 F.184 F.185 F.194 F.195 F.196 F.299 F.317 F.318 F.320 F.321 F.322 F.323 F.324 F.325 F.326 F.327 F.330 F.334 F.336 F.337 F.338 F.342 F.343 F.344 F.345 F.346 F.347 F.348 F.349 F.350 F.351 F.352 F.353 F.354 F.355 F.357 F.359 F.361 F.363 F.365 F.366 F.367 F.368 F.369 F.370 F.371 F.372 F.373 F.375 F.377 F.378 F.379 F.380 F.381 F.382 F.383 F.384 F.385 F.386 F.387 F.388 F.394 F.395 F.396 F.399 F.400 F.401 F.402 F.403 F.404 F.405 F.406 F.408 F.410 F.416 F.417 F.418 F.425 F.426 F.427 F.428 F.429 F.430 F.431 F.432 F.433 F.436 F.437 F.440 F.441 F.442 F.443 F.444 F.445 F.446 F.447 F.448 F.449 F.450 F.451 F.452 F.453 F.454 F.455 F.456 F.457 F.458 F.461 F.462 F.463 F.464 F.467 F.468 F.471 F.473 F.474 F.477 F.517 F.527 F.528 F.530 F.538 F.539 F.540 F.542 F.543 F.544 F.545 F.546 F.547 F.548 F.549 F.574 F.575 F.576 F.577 F.578 F.579 F.580 F.581 F.582 F.583 F.584 F.585 F.666 F.667 F.668 F.669 F.670 F.671 F.672 F.673 F.682 F.683 F.684 F.688 F.693 F.694 F.696 F.707 F.762 F.763 F.764 F.765 F.797 F.799 F.905 F.980 F.981 F.982 F0 F00 F000 F0 237-239 F0 238 F0 239 F0 258 F0 262 F0 263 F0 272 F0 280 F0 290 F0 d F0A F0b F0C F0U F1 F01 F001 F1 259 F1 263 F1 or F4 F1A F2 F02 F002 F2 1.25AT F2 Or Fn Or Ln F2A F3 F003 F03 F4 F04 F004 F04 L04 F4 Or L4 F4A F5 F05 F005 F05 L05 F5 Or L5 F5/F9 F6 F006 F06 F7 F07 F007 F7 228 F8 F08 F008 F8 or L8 F8/L8 F9 F09 F009 F9 C F09 L09 F9 n F9 or L9 F9 or L9 or F8 or L8 F9 SU F9/L9 F10 F010 F11 F011 F12 F012 F13 f014 F14 f015 F15 f016 F16 F17 F18 F018 F19 F019 F20 F21 F22 F23 F24 F25 F26 F27 F027 f028 F28 f029 F29 F30 F030 F31 F031 F32 F34 F35 F36 F37 F38 F39 F40 F41 F42 F43 F44 F45 F46 F47 F49 F50 F51 F51 - F53 F52 F53 F56 F56 – A56 F58 F59 F61 F61 – A61 F62 F63 F64 F65 F66 F67 F68 F68 – A68 F70 F71 F72 F73 F74 F75 F76 F77 F78 F81 F83 F84 F85 F86 F96 F99 F141 F201 FA FA 306 FA 364 FA9 FAIL POINT A FAIL POINT B FAIL POINT C FAIL POINT D FAIL POINT E FAIL POINT F FAIL POINT G FAIL POINT H FAIL POINT I FAIL POINT J FAIL POINT K FAILED PELLET LIGHTING FAILURE TO LIGHT False Flame Fault False Flame Lockout FAN Fan Connections Short Circuit Fan does not run Fan Error Fan Fault Fan Hunt FAN LOCKOUT FAN NEON Fan On Fan operation indicator Fan Overrun Fan Purge Fan runs Fan runs at max. speed Fan runs boiler does not work Fan speed Fan speed too low. Fan start up Fan/Flue LED Green fan/flue problem Fast flash Fast flash (Reset button Off) Fast flash / Flashing Fast flash / Not a fault code Fast flash / Off Fast flash, Lockout reset: Off Fast Flashing (8Hz) Fast flashing reset button Fault fault condition Fault indication light (2) Fault led (B) illuminated Fault light is on Fault on DHW sensor Fault on Fan or Flue Fault on gas feeding Fault on gas supply Fault on Hot Water Sensor Fault sensors Fault sensors CH Fault sensors DHW Faulty air pressure sensor Faulty air pressure switch Faulty condensate drainage Faulty fan Faulty flame detection Faulty gas valve Faulty ignition Faulty ignition device Faulty modulation gas valve Faulty PCB Faulty primary circuit Faulty sensor Fb Fb 365 Fb0 Fb8 FC FC1 FD Fd 231 FE FE94 FE95 FE96 FE97 FF1 FF2 FH fI- Fig. 14 Fig. 15 Fig. 16 Fig. 17 FIL FILL FILL (flashing) Filling Fixed red LED FL Flame FLAME CIRCUIT FAILURE FLAME Detected Flame detection error Flame detection fault Flame Failure Flame Failure (Red Light) Flame Failure (Red Light) ON FLAME FAILURE LED Flame Failure Neon Flame indicator flame lock-out Flame lockout Flame Loss Flame not detected. Flame ON Flame On Before Gas On Flame on before gas valve on FLAME ON BEFORE GV ON flame or gas fault Flash Flash 4 times per second Flash 8 times per second FLASH FLASH ON FLASH OFF FLASH FLASH OFF ON FLASH ON FLASH FLASH ON ON Flash once per second Flashes red Flashes red/green FLASHING Flashing 0.3 bar Flashing 8-times a second Flashing 30 Flashing 40 Flashing 50 Flashing 60 Flashing 70 Flashing 80 Flashing 90 flashing bar value Flashing digits Flashing dot D2 FLASHING F flashing FILL / HIGH Flashing Green Flashing lamp Flashing LD1 Flashing LD2 Flashing mains LED Flashing Mains ON light Flashing orange LED FLASHING P Flashing pressure flashing pressure value Flashing Red Flashing Red LED Float switch Flow Flow NTC sensor defective FLOW panel LED not lit with hot tap open Flow return reversed Flow sensor Flow Switch Flow Temperature Overheat Flow Temperature Overheat Lockout Flow Thermistor Flow Thermistor Fault Flow/Flue Thermistor Fault FLOW/RETURN SENSOR DRIFT ERROR FLOW/RETURN THERMISTOR FAULT Flue blockage Flue gas pressure switch Flue gas sensor faulty Flue overheat FLUE SENSOR Flue spillage device FLUE TEMPERATURE SENOR LOCKOUT Flue Thermistor Fault Fn FO FP FP 1 0 FR Frequent sooting (1) Frost protect operation FSK1 FU Fume thermostat activation FUSE Fuse 1 Fuse 2 fuse blown FWER
G (81 codes)
G2 G20 G30 G31 Gas injectors blocked Gas injectors plugged Gas On GAS TAP STIFF Gas Valve Fault GAS VALVE NOT OPENING Gas valve(s) GE45/90 GEB90 GEB200 GK90 GK90S GK200 GK200S GM001 GM002 GM003 GM004 GM007 GM008 GM012 GM013 GM044 Good GREEN Green 'Flame' led GREEN blinking GREEN blinking (0.5s) Green fast flashing Green flashing Green flashing + red flashing Green Flashing every 6-seconds GREEN LED BLINKS Green LED flashing GREEN LED Flashing 8-times a second Green LED Flashing 8-times every second Green LED Flashing every 6-seconds Green LED flashing rapidly (8/sec) Green LED illuminated Green LED Off, Red LED Off Green LED OFF, Red LED ON Green LED on GREEN LED on continuously Green LED On every 0.5 second Green LED on every 0.5 seconds GREEN LED ON every 0.5-secs Green LED on every 6 seconds GREEN LED ON every 6-secs Green LED ON, Red LED OFF Green LED On, Yellow LED On Green LED On/flashing GREEN LED Solid Green Light Green light 'On' only Green light flashes rapidly Green light flashing slowly Green light On continuously Green neon GREEN ORANGE blinking (0.5s) Green/Red - blinking Green/Red flashing Group 1, 1 flash Group 1, 2 flashes Group 1, 3 flashes Group 1, 4 flashes Group 1, 5 flashes Group 2, 6 flashes Group 2, 7 flashes Group 2, 8 flashes Group 2, 9 flashes Group 2, 10 flashes GTH90 GTH200 GTV90 GTV200 GWB90 GWB200
H (118 codes)
H 1 h 9 H 60 H A H A (flashing) H E H n H-- H.00 .81 H.00.42 H.01.00 H.01.05 H.01.08 H.01.14 H.01.18 H.01.21 H.02 .70 H.02.00 H.02.02 H.02.03 H.02.04 H.02.05 H.02.07 H.02.09 H.02.10 H.02.12 H.02.38 H.03 .54 H.03.00 H.03.01 H.03.02 H.03.05 H.03.17 H0 H00 266 H00 269 H00.00 H00.81 H1 H01.00 H01.05 H01.08 H01.14 H01.15 H2 H02.00 H02.02 H02.03 H02.04 H02.05 H02.09 H02.10 H02.12 H02.38 H02.70 H2o H03 H3 H03.00 H03.01 H03.02 H03.05 H03.17 H4 H5 H6 H7 H8 H08 H9 H09 H9/L9 H11 H13 h13/H13 H20-986 H21-048 H21-049 H21-052 H21-060 H21-064 H27-582 H29 HA Hb HC Hd HE HE DHW OUTLET SENSOR Heatbank Overheat Stat HEATING BODY NOISE Heating demand light OFF Heating demand light ON Heating LED (Green) HF HIGH High limit High limit thermostat High Mains Voltage High neon light High Pressure Sensor Error High Pressure Switch Operated High rate LED - yellow High rate LED flashing yellow HIGH SMOKE NUMBER HIGH WATER FLOW high water temperature HJ-09 HL Hot Surface Igniter Hot water demand indicator Hot water high limit stat Hot Water LED (Green) Hours hp Ht HW light On (flashing) HW light on PCB 40 flashing
I (70 codes)
I.003 I.020 I.55 I.56 I.57 I.59 I.93 I.144 i0 i1 i01 i2 i02 I2H i3 i4 i5 i6 i7 i8 i9 i10 i11 i12 i13 i14 i15 i19 i20 i21 i22 i23 Ignition failure Ignition fault Ignition indicator Ignition Lock-out Ignition Lock-out neon Ignition lockout Ignition Lockout 1/2 Ignition Lockout 2/2 IGNITION LOCKOUT INDICATOR Ignition Pre Checks II - Illuminated reset light Incorrect CO2 Incorrect gas rate Incorrect water flow rate Incorrect water temperature Indicator 1 (Reset) Lit Indicator 2 (Burner Lit) Lit Indicator LED - green Indicator LED - orange INDICATOR LIGHT FLASHING Indicator light inside box lit Indicator Neons Indicator: Reset/Standby lit Insufficient Circulation Insufficient pressure Insufficient System Pressure INSUFFICIENT WATER INSUFFICIENT WATER FLOW Insufficient water pressure Intermittent lockout Internal error. Internal fault Inverter Error Inverter High Current Inverter High Temperature IPX4D IPX5D
J (19 codes)
K (2 codes)
L (306 codes)
L (Flashing) L 0- L 0C L 0d L 01 L 1 L 02 L 2 L 04 L 05 L 06 L 6 L 9 L 09 L A L A (flashing) L C L E L F L F (flashing) L- L-E.D. L.016 L.022 L.025 L.032 L.095 L.096 L.097 L.105 L.144 L.194 L.195 L.196 L.319 L.320 L.322 L.343 L.E.D. D L.E.D. G L0 L1 L01 L1E L2 L02 L2E L3 L3E L4 L04 L4 or F4 L5 L05 L5 or F5 L5E L6 L06 L6E L7 L8 L9 L09 L11 L12 L31 L32 L34 L43 L45 L46 L47 L52 L61 L65 LA LA/HA Lack of burner ignition Lamps flashing Last fault stored LB7 LBC LBE LC LC1 LC2 LC3 LC4 LC5 LC6 LC7 LC8 LC9 LCA LCB LCD LCE Ld LD1 LD1, LD2 Flashing LD1, LD2, LD3 Flashing LD2 LD2, LD3 Flashing LD3 LE LED 1 LED 1 (RESET) Constant Light LED 1 & 2 Simultaneous Lit LED 1 Fast Flashing (8Hz) LED 1 fast pulse LED 1 green (0) LED 1 Lit, LED 2 Off LED 1 Off, LED 2 Lit LED 1 ON (RESET) LED 1 Slow Flashing (2Hz) LED 1-2-3-4 (◯◯◯●) LED 1: 0 LED 1: Off, LED 2: On LED 1: On, LED 2: Off LED 1: On, LED 2: On LED 2 LED 2 (A) LED 2 (B) LED 2 (C.H.) LED 2 (CH) LED 2 (D.H.W.) LED 2 (DHW) LED 2 Burner Lit LED 2 Fast Flashing (8Hz) LED 2 goes OFF LED 2 OFF briefly LED 2 ON LED 2 ON (BURNER LIT) LED 2 on P.C.B. alight LED 2 on PCB 41 lit LED 2 Slow Flashing (2Hz) LED 2 yellow (0) [DHW mode] LED 2 yellow (1) [CH mode] LED 2: 0 LED 2: 1 LED 3 LED 3 (B) LED 3 (CH) LED 3 OFF (DHW Mode) LED 3 yellow (0) [CH mode] LED 3: 0 LED 4 LED 4 (A) LED 4 (B) LED 4 (C.H.) LED 4 (CH) LED 4 (D.H.W.) LED 4 (DHW) LED 4 (Flashing light) LED 4 (Flashing) LED 4 (Permanent light) LED 4 (Permanent) LED 4 flash/second LED 4 Flashing (DHW Mode) LED 4 green (0) [CH mode] LED 4 green (0) [DHW mode] LED 4: 0 LED 4: 0 (Central Heating) LED 5 LED 5 (A) LED 5 (B) LED 5 (CH) LED 5 (DHW) LED 5 (Flashing light) LED 5 (Flashing) LED 5 (Permanent light) LED 5 (Permanent) LED 5 bar (Flashing light) LED 5 bar (Permanent light) LED 5 ON LED 5 red (1) [CH mode] LED 5 red (1) [DHW mode] LED 5: 1 LED 5: 1 (Central Heating) LED 6 LED 6 (A) LED 6 (B) LED 6 (C.H.) LED 6 (CH) LED 6 (D.H.W.) LED 6 (DHW) LED 6 yellow (0) [CH mode] LED 6 yellow (0) [DHW mode] LED 6: 0 LED 6: 0 (Central Heating) LED 7 green (0) LED 7: 0 LED 8 yellow (0) LED Flashing LED flashing after fan LED off LED1 LED1 (green) LED1 flashing, LED2 on LED1 on LED1 on, LED2 flashing LED2 LED2 flashing, LED3 on LED2 on LED2 on PCB 37 LED2-5 (yellow) LED3 LED3 on LED3 on PCB 37 LED4 LED4 flashing LED4 permanent LED5 (Permanent) LED5 bar (Flashing) LED5 flashing LED5 on LF Lh Li Li 01 Li01 Light off Light ON Lights: Flash, Flash, On Lights: Flash, Off, Flash Lights: Flash, Off, On Lights: Flash, On, Flash Lights: Flash, On, On Lights: Off, Off, Off Lights: On Off On Lights: On On On Lights: On, Flash, Flash Lights: On, Flash, On Lights: On, Off, Flash Lights: On, On, Flash Limescale Build-up Limit Limit stat tripped limit thermostat Limit thermostat intervention LLL Ln LO2 Lock lamp / lock state Lock Out After 15 Seconds Lock out radiator light Lock state lock-out Lock-out (light on) Lock-out (Red neon) Lock-out lamp lock-out light Lock-out reset button is lit lock-out signal lamp Lock-out signal lamp 6 Lock-out signal lamp E blinks Lock-out signal lamp ON Lock-out signal lamp red Lock-out signal lamp red (ON) Lock-out state lockout Lockout (LED Mode) Lockout (Rapid Flashing Red) Lockout (rapid flashing) Lockout (Red LED) Lockout (Red) flashing Lockout (Red) light flash Lockout (Red) light is on Lockout (Red) light on Lockout (Red) light will flash Lockout button lit Lockout error Lockout fault Lockout flame signal Lockout Lamp Lockout lamp (red) on Lockout lamp illuminating (Overheat Thermostat) Lockout LED lockout LED 2 ON Lockout LED continuously on Lockout light LOCKOUT LIGHT FLASHING Lockout light illuminated Lockout light on LOCKOUT LIGHT ON (CONSTANTLY) Loss of system water pressure Loss of water indicating light Low mains voltage Low neon light LOW POWER SUPPLY FROM MAINS Low Pressure Error LOW PRESSURE indicator lit Low pressure safety trip Low system pressure Low System Pressure light Low system pressure neon lit low water pressure Low water pressure LED Low water pressure LED flash Low water pressure light ON LOW WATER SWITCH LOW WATER TEMPERATURE low-pressure Low-pressure fault code LP Lt
M (15 codes)
Main burner does not light Main burner not operating (all neons lit) main burner operating Main burner will not light Mains fuse F2 on PCB 40 blown Mains LED flashing Mains LED off Mains LEDs Mains light Mains On (Green Light) Mains On (Green) light flash Mains On neon not lit Mains ON Only max err . Microprocessor faulty
N (131 codes)
N.013 N.027 N.032 N.089 N.095 N.096 N.097 N.100 N.144 N.194 N.270 N.317 N.319 N.324 N.343 n1 n2 n3 n4 n5 n6 n7 n8 n9 neon '12' illuminated Neon 1 Neon 1 lit Neon 1 lit (NO) Neon 1 NOT lit Neon 2 Neon 2 lit Neon 2 lit (NO) Neon 2 NOT lit Neon 3 Neon 3 lit Neon 3 lit (NO) Neon 3 NOT lit Neon 4 Neon 4 lit Neon 4 lit (NO) Neon 4 NOT lit Neon A flashing Neon B flashing Neon B Flashing very slowly Neon D Neon D illuminated Neon D NOT illuminated neon flashing neon flashing (1st instance) neon flashing (2nd instance) neon flashing (3rd instance) neon flashing (4th instance) neon flashing (5th instance) neon flashing (Burner lights) neon flashing (Fan runs) neon flashing (Fan) Neon flashing (Generic) neon flashing (Overheat) neon flashing (Pump runs) neon flashing (Section B) neon flashing (Section B/C) neon flashing (Section C) neon flashing (Section D) neon flashing (Section E) neon flashing (Section F) neon flashing (Section H & K) neon flashing (Section I) neon flashing (Section I/M) neon flashing (Section J) neon flashing (Section J/M) neon flashing (Section M) neon flashing (Spark/Ignition) neon I 1 neon I 2 Neon I1 Neon I2 Neon I3 Neon illuminated (Burner) Neon l1 Neon l2 Neon l3 Neon L4 Neon L5 Neon L6 Neon SG Neon SG1 Neon SGI Neon1 Neon2 Neon3 Neon4 NEON5 Neon6 neons flashing (Section D) No burner ignition NO CH BUT DHW OK NO CH OPERATION NO CONNECTION TO PRIMARY PCB NO DHW BUT CH OK NO DHW BUT CH ON No DHW temperature control No Display No Flashes (after 15 seconds) No flow No HW but CH OK No LED No light No light (DHW cold) No light / Not a fault code No light display when tap on No light indication No lightindication No mains LED No neon illuminated No oil from nozzle No Switched Live No Water Flow NO WATER FLOW FAULT No water flow lockout No Water Flow Thermistor no. 46 no. 47 no. 48 Noise Noises in CH system Noisy operation None Normally operating boiler Not a fault code NOT OPERATING IN HEATING MODE NTC heating probe
O (82 codes)
o OBCD OC OF OFF Off (No light) Off / Off OFF OFF OFF OIL SMELLS ON On * On Off On / Off ON every 0.5-secs ON every 0.5-secs (RED LED) ON every 0.5-secs (YELLOW LED) ON every 6-secs ON every 6-secs (GREEN LED) ON FLASH FLASH ON FLASH ON ON OFF FLASH ON OFF ON On Off On Off ON ON FLASH ON ON ON Operation lights flashing OPTIMAX HE PLUS 38C ORANGE Orange 'Mains' light ORANGE blinking Orange LED Orange LED flashing Orange LED on Orange Light Orange light (Boiler fault) Orange light (first) Orange light (second) Orange light (single) Orange light (third) Orange neon OT ERROR OTER Other defects Other faults OUTDOOR SENSOR ERROR Outlet sensor faulty Outside sensor Outside Sensor Failure Outside Sensor Fault Over temperature Over-run Overcurrent Protection Error Overheat Overheat - Red LED: FLASHING Overheat (Red LED) Overheat condition Overheat cut-off Overheat Detection overheat fault OVERHEAT HIGH LIMIT Overheat indicator light Overheat LED Overheat LED flashing Overheat LED illuminated Overheat light Overheat light on Overheat Limit Thermostat OVERHEAT LOCKOUT Overheat Lockout 1/4 Overheat Lockout 2/4 Overheat Lockout 3/4 Overheat Lockout 4/4 OVERHEAT LOCKOUT INDICATOR Overheat Neon Overheat Neon Illumination OVERHEAT panel LED lit Overheat safety trip Overheat Stat neons flashing Overheat thermostat Overheat thermostat activated Overheat thermostat lockout Overheating Overheating safety
P (179 codes)
P (flashing) p < 0.5 P 0.4 P 0.9 p 1.5 P 3.1 P 3.1 or higher P 15 P 32 P 33 P 34 P 35 P blinking P x.x P.00 P.0 P.000 P.01 P.1 P.02 P.2 P.03 P.3 P.04 P.4 P.05 P.5 P.06 P.6 P.07 P.8 P.008 P.08 P.10 P.11 P.12 P.13 P.14 p/-.- P00 P0 P0.1-0.4 P0.1-0.4 bar P0.5-0.9 P0.5-0.9 bar P1 P01 P1.0-2.9 P1.0-2.9 bar P1.6 P2 P02 P3 P03 P3.0-3.5 P3.0-3.5 bar P04 P4 P05 P5 P06 P7 P07 P08 P09 P10 P11 P12 P13 P14 P15 P16 P17 P18 P19 P20 P21 P22 P23 P24 P25 P26 P27 P28 P29 P30 P31 P32 P33 P34 P35 P36 P37 P38 Pb PCB 38 CH light flashing PCB 38 HW light flashing PCB Fault PCB Fault / Contact Installer PCB REPLACED Pd PELLET FEED TUBE STAT TRIPPED Peripheral / Pump LED Green Permanent Live PH PH 60 Phase reversed neon Phase reversed neon (behind the knob) lighting Pictogram of a spark Pilot being extinguished Pilot does not light Pilot does not remain alight Pilot does not stay alight Pilot extinguishes Pilot Fault Finding PILOT FLAME DOES NOT LIGHT Pilot On Pilot On light Pilot On light on Pilot will not light Pilot will not light (1) Pilot will not light (2) PILOT WILL NOT STAY ALIGHT Pilot/Ignition LED Green PO POINT D POINT I POOR PILOT FLAME power POWER LED Power LED Green Power Neon (Flashing) Power On Power On (Green LED) Power ON (Green LED) blinking Power on indicator Power On LED Power ON LED (Green) Power ON LED (Green) blinking Power On Neon PP/-- PP/AA PP/LL Pr 29 Pr 30 Pr00 Pr12 Preheat control neon flashing Preheat neon flashing Pressure < 0.5 bar Pressure fall below 0.5 BAR Pressure of 3 or greater Primary flow switch operated primary NTC open/short circuit PROBE FAULT Pulsation on start Pulse Red (1 flash) Pulse Red (2 flashes) Pulse Red (3 flashes) Pulse Red (4 flashes) Pulse Red (5 flashes) Pulse Red (6 flashes) Pump Pump antiseize Pump circulating water / No Pump Dry Run Pump failure PUMP FAULT Pump Fault or Low Pressure Pump has run dry. PUMP LOW VOLTAGE FAULT PUMP NOT RUNNING Pump Overrun Pump Overrun - Central Heating Pump Overrun - Storage Tank Pump rotor blocked Pump runs Pump/Low Pressure Neon Purge cycle mode active
R (130 codes)
r1 R867A R7627 Radiators cold in winter Rapid flashes rb rE rE44 Red - blinking Red - continuous Red 'Flame Failure' neon lit RED & GREEN lights flashing RED & GREEN lights OFF Red | On every 0.5 second red ● Red 0.2s ON RED 0.5s ON RED blinking (0.5s) RED fast blinking RED fast blinking (0.2s) RED flashing (Reset button) Red flashing light Red flashing light (Flue) Red flashing light (Gas) Red flashing running lamp Red indicator Red indicator illuminates Red indicator lit Red L.E.D. I illuminated Red LED Red LED (illuminated) Red LED (Lockout) Red LED (Overheat) Red LED (TTB) Red LED after flow switch RED LED BLINKS Red LED five flash sequence Red led fixed Red LED flashing Red LED flashing every 0.5 seconds Red LED I Red LED I (Overheat) Red LED illuminated (Lockout) Red LED illuminated (Overheat) Red LED illuminated (TTB) Red LED is 'ON' RED LED LIGHT Red LED On Red LED on (after safety stat) Red LED on (solid) RED LED on continuously Red LED On every 0.5 second RED LED ON every 0.5-secs Red LED on only Red LED On permanently Red LED on/Flashing Red LED Out (Lockout) Red led permanently on Red LED rapid flashing RED LED Solid Red LED two flash sequence Red LED: Flashing Red Red Light Red light (Egg timer symbol) Red light (flashing) Red light F ON Red light flashes Red light flashing (Lockout) RED LOCKOUT BUTTON Red lockout indicator Red lockout indicator bulb RED lockout led Red lockout light Red lockout light F red lockout neon Red lockout neon (lit) Red neon Red neon (A) flashing Red neon (on panel) Red neon illuminated Red neon light Red neon lit Red neon on fascia Red neon on fascia illuminated Red operational light 2 (E) Red reset button illuminated Red reset neon (lit) RED steady ON RED, GREEN blinking inverted RED, ORANGE blinking inverted Relay 2 energised after 2 sec REMOTE RESET LOCKOUT Repair Repeated ignition failure Reset Reset Button Illuminated Reset LED is lit Reset light Reset Light (Ignition) Reset light (illuminated) Reset Light / Overheat Reset light is on Reset light on Reset neon Reset Neon (Flashing) Reset neon does not extinguish Reset neon illuminated (Red) Reset neon is lit Reset neon lights Reset the boiler Return sensor Return sensor faulty Return Thermistor Return Thermistor Fault Return Thmr Fault Reverse polarity Reversed Polarity Room Stat Fault Room Thermostat Fault RSL40 RSL50 RSL60 RSL70 RSL80 RSL90 RSL100 Run Running lamp flashing RY2 RY4
S (213 codes)
S 80 S.0 S.00 S.000 S.01 S.1 S.001 S.02 S.2 S.002 S.03 S.3 S.003 S.04 S.4 S.004 S.05 S.5 S.005 S.06 S.6 S.006 S.07 S.7 S.007 S.08 S.8 S.008 S.009 S.09 S.9 S.10 S.010 S.11 S.011 S.012 S.13 S.013 S.14 S.014 S.15 S.015 S.16 S.016 S.17 S.017 S.019 S.19 S.20 S.020 S.21 S.021 S.22 S.022 S.23 S.023 S.24 S.024 S.25 S.025 S.26 S.026 S.27 S.027 S.28 S.028 S.029 S.29 S.30 S.030 S.31 S.031 S.32 S.032 S.33 S.34 S.034 S.35 S.36 S.37 S.39 S.039 S.40 S.41 S.041 S.42 S.042 S.46 S.52 S.53 S.54 S.054 S.55 S.56 S.57 S.057 S.58 S.59 S.059 S.60 S.61 S.62 S.63 S.74 S.75 S.76 S.85 S.86 S.88 S.088 S.90 S.91 S.091 S.92 S.092 S.93 S.093 S.94 S.95 S.96 S.096 S.97 S.097 S.98 S.098 S.99 S.108 S.109 S.154 S.175 S.199 S.326 S.328 S.335 S.341 S.599 S.O S3 S13 SAFETY HIGH LIMIT THERMOSTAT Safety indicator (4) lights Safety limit stat Safety LOCK-OUT Safety Lock-out LED Safety Lockout (Red LED) Safety Lockout LED (Red) Safety shut-down Safety Shut-off Safety system failure Safety temperature limiter Safety Thermostat Safety thermostat activated Safety thermostat lock out Safety thermostat lockout Safety Thermostat Neon Sc14 SE Second orange light Sensor Sensor Fault Sensor Fault Neon Sensor Fault Neons Sensor Faults Sensor Flow Sensor Flow or return sensor SENSOR STUCK LOCKOUT SERVICE Service Due Service operation Service Required SERVO MOTOR BLOCKED SET SF SFS SG1 SH Short Cycling Shorted signal Shut down SI1 SI2 SI3 SL Slow flash Slow flash (normally off) Slow flash (unspecified rate) Slow flashes Slow Flashing (2Hz) Slow flashing reset button Smell of unburnt gas So Software Error Solid Solid (RED LED) Solid (YELLOW LED) SOOT FORMED Spare PCB Not Set Spark at ignition electrodes Sr ST6 ST10 ST19 Stand-by STANDBY STANDBY NEON StBY Steady on (Burner lit) STOP Su Summer mode LED SUMP FAN FAILURE THERMOSTAT Switched Live Sy
T (55 codes)
t - T.001 T.01 T.02 T.03 T.04 T.05 T.06 T.007 T.08 T1 T1/T2 t2 T2B t3 T3.15A t4 t6 T7 T8 t80 Tap symbol light OFF Tap symbol light ON TEC Telephone symbol Temperature Control Temperature control lockout Temporary fault Test 1 Test 1A Test 2 Test 3 Test 4 Test1 Test2 Test3 Test4 tf Thermal fuse lockout THERMISTOR THERMISTOR FAULT Thermostat + Third orange light Too many resets Too Many Restarts Troubleshooting 19 Troubleshooting 20 Troubleshooting 21 Troubleshooting 22 tst - 100 TTB Downdraught Thermostat Tw_Out Two red lights flash rapidly Type A Type E
U (13 codes)
V (7 codes)
W (22 codes)
WAIT BOILER THERMOSTAT WAIT PELLET THERMOSTAT Water Circulation LOCKOUT WATER OVERHEAT THERMOSTAT Water pressure Water Pressure 1/3 Water Pressure 2/3 Water Pressure 3/3 WATER PRESSURE SENSOR water pressure switch WATER PRESSURE TOO HIGH WATER TEMPERATURE WATER TEMPERATURE LOW Water temperature too cool Water temperature too hot White reset neon illuminated Wiring fault Wiring Harness Wrench symbol Wrench symbol flashing Wrong Fan Fitted Wrong Fan Motor Fitted
X (2 codes)
Y (12 codes)
Z (1 codes)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026