BoilerFaultCodesThe 5 most common faults
01
lock out High Engineer
Your boiler has stopped working because it cannot detect a flame, most likely because the gas supply is interrupted or there is air trapped in the pipes.
Full guide for lock out02
Burner lockout indicator (red) High Engineer
Your boiler has stopped working because it failed to ignite, which could be due to a gas supply issue, a lack of water pressure, or an internal mechanical fault.
Full guide for Burner lockout indicator (red)03
Power on indicator (green) Low DIY-safe
Your boiler is receiving power and is currently switched on, which is the normal state for the unit to be in.
What to try first
No action is required as this simply confirms the boiler has electricity.If you have no heating or hot water, check your programmer or thermostat settings instead.
04
Ignition indicator (yellow) Low Engineer
The yellow light simply means your boiler is currently working correctly to heat your home or provide hot water.
Full guide for Ignition indicator (yellow)05
Flame indicator (yellow) Low Engineer
This light simply shows that your boiler has successfully ignited and is operating normally.
Full guide for Flame indicator (yellow)on the Vaillant Turbomax VUW 242/1
Ignition electrodeGas valvePCBCirculation pumpFlow switch
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 Vaillant 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