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
L A High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage or safety issues.
Full guide for L A04
L 8 High Engineer
Your boiler has detected an issue with the internal air circulation system, meaning it cannot safely clear waste gases and has shut down to prevent risk.
Full guide for L 805
H 1 High Engineer
Your boiler's temperature sensor is reporting an inconsistent or faulty reading, causing the system to stop working as a safety precaution.
Full guide for H 106
H 2 High Engineer
Your boiler has detected a serious internal system error that requires a professional engineer to investigate.
Full guide for H 2on the Ideal Isar M30 / M100
Ignition ElectrodeFlame Rectification ProbeGas ValveMain Printed Circuit Board (PCB)Overheat ThermostatNTC Sensor
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