BoilerFaultCodesThe 6 most common faults
01
Ignition Lockout High Engineer
Your boiler has failed to start because it cannot detect a flame, so it has safely shut itself off to prevent gas being released.
Full guide for Ignition Lockout02
Lights: Off Off Off High Engineer
Your boiler has lost all power and is completely unresponsive as if it has been unplugged.
Full guide for Lights: Off Off Off03
Lights: On Flash Flash High Engineer
Your boiler has detected that there is not enough water inside the system to operate safely, which has caused it to shut down to prevent damage.
Full guide for Lights: On Flash Flash04
Lights: Flash On Flash High Engineer
Your boiler has detected an internal computer error and needs a professional repair to function again.
Full guide for Lights: Flash On Flash05
Lights: On On Flash High Engineer
Your boiler's electronic command center has encountered a critical internal error and can no longer safely control the heating or hot water system.
Full guide for Lights: On On Flash06
Lights: Flash On On High Engineer
Your boiler’s internal control system has detected a critical electronic failure, meaning it can no longer safely operate or heat your home.
Full guide for Lights: Flash On Onon the Potterton Promax HE Store
Ignition electrodeGas valvePrinted Circuit BoardPCBInternal FuseWiring 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 Potterton 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