BoilerFaultCodesThe 4 most common faults
01
e1 High Engineer
Your boiler's temperature sensor is providing faulty information, causing the system to stop operating as a safety precaution.
Full guide for e102
e2 High Engineer
Your boiler has detected a communication issue with a sensor in its exhaust pipe, so it has safely shut down to prevent potential overheating.
Full guide for e203
e5 High Engineer
Your boiler has stopped working because the burner failed to ignite or stay lit, meaning you currently have no heating or hot water.
Full guide for e504
Burner Lockout High Engineer
Your boiler has stopped working for safety reasons and needs a manual reset or a professional to investigate why it failed to light.
Full guide for Burner Lockouton the Firebird Envirogreen Regular
NTC ThermistorWiring harnessFlue gas temperature sensorWiring harness / Probe loomPhotocellIgnition electrodes
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 Firebird 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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