What does the Worcester Bosch t4 fault code mean?

Your boiler is currently running a background self-test to ensure the internal component that switches between heating your radiators and heating your hot water is working correctly.

How much does it cost to fix Worcester Bosch error code t4?

Typical repair cost for the Worcester Bosch t4 fault is £150-250 including labour.

Worcester Bosch t4 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Three way valve test. Test the operation of the diverter valve. When 1 is selected via the test menu the diverter valve will move to the DHW position. When 0 is selected the valve will move to CH position.

Shared across the Greenstar range

This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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All 365 fault codes on the Greenstar CDi Compact

Seeing a different code? Every code this model can display, in one place.

1.A 1.b 1.C 1.d 1.E 2.b 2.C 2.F 3.b 3.C 3.E 3.F 4.F 5.A 5.b 6.d 6.E 8.A 8.b 8.C 8.E 8.F 8E 9.A 9.b 9.C 9.d 9.E 9.F 9U 10 12 13 14 15 20 21 30 40 42 43 53 54 56 100 101 102 103 104 117 118 119 121 122 123 124 125 126 127 128 131 132 133 170 171 200 201 202 203 204 205 207 207 / CE 208 210 210 / 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 225 227 227 / EA 228 228 / F7 229 229 / EA 230 230 / EA 231 231 / FD 232 232 / D3 233 233 / 9U 234 234 / EA 237 237 / C4 238 238 / F0 238 F0 239 239 / F0 239 F0 240 240 / D1 240 D1 241 241 / D1 241 D1 242 256 257 257 / b7 257 b7 258 259 260 261 261 / EA 261 EA 262 263 264 264 / C1 264 C1 265 266 266 / CE 266 CE 267 267 / F0 267 F0 268 269 269 / EA 269 EA 270 271 271 / D4 271 D4 272 272 / F0 272 F0 273 273 / C4 273 C4 274 276 276 / E9 276 E9 277 277 / E9 277 E9 278 278 / F0 278 F0 279 279 / F0 279 F0 280 280 / F0 280 F0 281 281 / A1 281 A1 282 282 / H5 282 H5 283 284 285 285 / E9 285 E9 286 286 / D1 286 D1 287 287 / F0 287 F0 288 288 / CF 288 CF 289 289 / CF 289 CF 290 290 / F0 290 F0 305 306 306 / FA 306 FA 307 308 309 310 311 312 313 314 315 316 316 / E9 316 E9 317 317 / A3 317 A3 318 318 / E9 318 E9 321 322 323 323 / A8 323 A8 324 325 326 327 328 329 329 / CE 329 CE 332 332 / E5 332 E5 333 338 338 / F0 338 F0 341 341 / D4 341 D4 342 342 / D4 342 D4 343 343 / ED 343 ED 344 344 / ED 344 ED 345 345 / EF 345 EF 346 346 / EC 346 EC 347 347 / E3 347 E3 348 348 / EE 348 EE 349 349 / EF 349 EF 350 350 / E2 350 E2 351 354 357 358 359 364 364 / FA 364 FA 365 365 / Fb 365 Fb 372 373 373 / 8C 373 8C 374 374 / 8C 374 8C 375 375 / E4 375 E4 376 376 / E4 376 E4 380 800 800 / CC 800 CC 808 808 / A7 808 A7 810 828 A1 A1 281 A7 A8 b1 b7 C1 C1 264 C4 C4 273 C6 C7 D1 D1 240 D4 D4 271 E2 E5 E9 E9 219 E9 224 EA EA 227 EF EF 349 F0 F0 237-239 F0 263 F7 F7 228 FA FA 306 FA 364 Fb Fb 365 Fd FD 231 P1 P2 P3 P4 PC SE t1 t2 t3 t6

Your boiler is currently running a background self-test to ensure the internal component that switches between heating your radiators and heating your hot water is working correctly.

What the manual says

Engineer required

Avoid the next call-out bill

All 365 fault codes on the Greenstar CDi Compact

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