Common problems guide

The most common Viessmann Vitodens 050-W B0KA-30 problems

The faults most likely to send a Viessmann Vitodens 050-W B0KA-30 into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

131 documented codes
6 most common
0 DIY-safe checks
6 engineer needed

The 6 most common faults

01
59 High Engineer

Your boiler has stopped because its fan is not reporting its speed correctly, so it has shut itself down as a safety precaution, and a qualified engineer should check it.

Est. cost
£150-400
Parts
Fan assembly, Fan power or connecting cable, Fan speed sensor (Hall sensor)
Full guide for 59
02
457 High Engineer

Your boiler's fan is turning on but the control system isn't getting the speed confirmation it needs, so the boiler has stopped to stay safe, and a Gas Safe engineer should check it.

Est. cost
£250-450
Parts
Combustion fan assembly, Fan connection cable or wiring harness, Fan gasket or air/gas mixing unit seal
Full guide for 457
03
359 High Engineer

Your boiler is trying to light its burner but cannot get it started, so it has stopped working and is not providing heating or hot water until a qualified engineer checks it.

Est. cost
£180-350
Parts
Ignition module (HBMU control unit), Ignition electrode, Ignition lead
Full guide for 359
04
357 High Engineer

Your boiler's gas valve didn't open when it should, so the boiler can't light and you may have no heating or hot water until it's checked.

Est. cost
£180-400
Parts
Gas valve assembly (gas solenoid valve), Gas valve diaphragm, Gas filter
Full guide for 357
05
369 High Engineer

Your boiler has stopped because it is not detecting its flame properly, so it has shut itself down as a safety precaution and needs a qualified engineer to check it.

Est. cost
£100-220
Parts
Ionisation electrode, Burner gauze assembly gasket, Burner door seal
Full guide for 369
06
380 High Engineer

Your boiler has shut itself down for safety because it is having trouble detecting its gas flame, which means it is probably not giving you heating or hot water until a registered engineer checks it.

Est. cost
£120-250
Parts
Ionisation electrode, Burner gauze assembly gasket, Ignition electrode
Full guide for 380
Parts most often replaced

on the Viessmann Vitodens 050-W B0KA-30

Fan assemblyFan power or connecting cableFan speed sensor (Hall sensor)Control PCB (if the fault persists after cable and fan checks)Combustion fan assemblyFan connection cable or wiring harness

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Viessmann shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue
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See the full 131-code list for the Viessmann Vitodens 050-W B0KA-30

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →