BoilerFaultCodesThe 6 most common faults
01
01 High Engineer
Your boiler has detected an electrical fault in its internal wiring, which has caused it to shut down to prevent further damage.
Full guide for 0102
02 High Engineer
Your boiler has failed to light the burner after several attempts, so it has shut down for safety reasons to prevent a gas build-up.
Full guide for 0203
04 High Engineer
Your boiler's electronic brain has encountered an internal error and has safely shut down to prevent further issues.
Full guide for 0404
08 High Engineer
Your boiler is struggling to clear air out of its system or is failing to pull in enough fresh air to burn correctly, causing it to shut down for safety.
Full guide for 0805
12 High Engineer
Your boiler's internal computer has encountered a software or communication error and has safely shut itself down to prevent damage.
Full guide for 1206
18 High Engineer
Your boiler has detected that the water inside the system is getting dangerously hot and has shut itself down to prevent damage.
Full guide for 18on the Remeha W40
Main Control BoardWiring HarnessSensorIgnition electrodeGas valveIonisation probe
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 Remeha 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