What does the Viessmann 346 fault code mean?

Your boiler has stopped itself because it could not finish checking how it burns gas safely, which usually means a small adjustment or cleaning is needed rather than a major failure.

How much does it cost to fix Viessmann error code 346?

Typical repair cost for the Viessmann 346 fault is £120-280 including labour.

Viessmann 346 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Automatic calibration of the combustion controller – No: Check gap between ionisation electrode and burner gauze assembly. Check the flue system. Remove flue gas recirculation if necessary. Reset the appliance.

From this model's manual

Verified against the Viessmann/Viessmann Vitodens 050 W B0ha B0ka 6194588 installation & service manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register →

Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 346: no call-out fees, no surprise bills.

Approved partner

Domestic Appliance Guard

Unlimited call-outs, 24/7 helpline, no price-hike promise

Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

345View →347View →

All 131 fault codes on the Vitodens 050-W B0KA-25

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

7 8 13 14 49 50 57 58 59 62 63 64 67 68 69 70 71 72 73 74 75 77 78 87 89 95 104 142 161 163 182 183 184 299 347 348 349 350 351 352 353 354 355 357 359 361 364 365 366 367 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 393 394 399 400 401 402 403 404 405 406 408 410 416 417 418 425 446 447 448 449 450 451 452 453 454 455 456 457 458 461 462 463 464 467 468 471 474 527 528 540 574 575 576 577 578 579 682 683 684 694 738 766 767 799 979 980 981 982 E10 E12

Your boiler has stopped itself because it could not finish checking how it burns gas safely, which usually means a small adjustment or cleaning is needed rather than a major failure.

What the manual says

Engineer required

Avoid the next call-out bill

Related fault codes

All 131 fault codes on the Vitodens 050-W B0KA-25

Related guides you might find useful

When to replace your boiler

Is boiler cover worth it?

Boiler service cost

Recently viewed