BoilerFaultCodesThe 6 most common faults
01
F.59 High Engineer
Your boiler has stopped heating because its internal fan is not running correctly, which is a common fault that a registered engineer can usually fix.
Full guide for F.5902
F.457 High Engineer
Your boiler has stopped because its internal ventilation fan is not starting up, which it needs to do safely before it can heat your home or water.
Full guide for F.45703
F.359 High Engineer
The boiler tried to light its burner but couldn't get a flame, so it has shut itself down to stay safe and needs a qualified engineer to check the ignition and gas supply.
Full guide for F.35904
F.357 High Engineer
Your boiler has stopped because it isn't getting the gas pressure it needs to light safely, so it's shut itself down to protect you and your home.
Full guide for F.35705
F.368 High Engineer
The boiler is not getting the gas pressure it needs to light, so it has stopped and is waiting for the gas supply to be checked.
Full guide for F.36806
F.369 High Engineer
The boiler's flame sensor is picking up a faint electrical signal even though no flame is burning, so the boiler has switched itself off as a safety precaution.
Full guide for F.369on the Viessmann Vitodens 200-W B2KE-19
Fan assemblyFan connection cable or harnessGas valve or gas-air mixing unitControl PCBCombustion 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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