BoilerFaultCodesThe 6 most common faults
01
Neon 1 High Engineer
Your boiler has detected that the internal fan system is stuck on or the air sensor is giving an incorrect reading before the boiler has even started.
Full guide for Neon 102
overheat stat trips High Engineer
Your boiler is getting too hot and triggering a safety switch to shut it down to prevent damage.
Full guide for overheat stat trips03
neon '12' illuminated High Engineer
Your boiler has detected that a vital internal temperature sensor is disconnected or has failed, preventing it from heating your home safely.
Full guide for neon '12' illuminated04
fuse blown High Engineer
Your boiler has lost power completely because an internal electrical safety fuse has popped, likely due to a wiring fault.
Full guide for fuse blown05
no line supply on violet lead High Engineer
Your boiler has lost power to an internal safety sensor, meaning it cannot confirm the fan is working and will not ignite for your safety.
Full guide for no line supply on violet lead06
no live supply on red lead High Engineer
Your boiler has lost power to an internal safety sensor, meaning it cannot start the ignition process for your heating or hot water.
Full guide for no live supply on red leadon the Ideal Classic NF
Air Pressure SwitchWiring HarnessFanControl thermostatLimit thermostat (Overheat stat)Pump
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