BoilerFaultCodesThe 6 most common faults
01
L F High Engineer
Your boiler is failing to light the flame or keep it running, which means it has safely shut itself down to prevent gas from building up.
Full guide for L F02
L E High Engineer
Your boiler's main computer control panel has detected an internal error, which means the system has safely shut down to prevent damage.
Full guide for L E03
H E High Engineer
Your boiler's main control unit has identified an internal electronic error and has shut down for safety to prevent unpredictable system behaviour.
Full guide for H E04
L-F High Engineer
Your boiler is failing to ignite the internal flame, which means it cannot produce any hot water or heating.
Full guide for L-F05
65 High Engineer
Your boiler has detected that the internal air extraction system is not working correctly, which prevents it from igniting safely.
Full guide for 6506
67 High Engineer
Your boiler has detected an internal electrical fault near the part responsible for sensing the flame, preventing it from safely starting up.
Full guide for 67on the Ideal Isar M30 / M100
Ignition ElectrodeFlame Rectification ProbeGas ValveMain Printed Circuit Board (PCB)Printed Circuit Board (PCB)Ignition electrode
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 Ideal 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