BoilerFaultCodesThe 6 most common faults
Your boiler is losing the water pressure it needs to work properly, which usually means there is a leak somewhere in your radiators, pipes, or the boiler itself.
Check all visible radiator valves and pipework for signs of dampness or dripsLocate your filling loop (usually a silver flexible hose) and carefully turn the valves to top up the pressure back to 1.5 barMonitor the pressure gauge over the next 24 hours to see if the needle drops again
Your boiler has switched itself off completely because it has gotten too hot, which is a safety feature designed to prevent damage.
Check that all radiator valves are fully open to allow water to flow.Wait 30 minutes for the boiler to cool down completely.Press the small reset button located on the overheat thermostat (usually found behind the front bottom panel).
Your boiler has switched itself off because it has become too hot inside, likely due to a circulation problem or a component failure.
Check that all radiator valves are fully openEnsure the system water pressure is at roughly 1.5 barOnce the boiler has cooled down, press the overheat reset button located on the controls
Your boiler's small pilot flame is failing to stay on, which prevents the system from firing up to provide heating or hot water.
Full guide for 52Your boiler's small pilot light is working, but the main burner is failing to ignite to provide heat or hot water.
Full guide for 53Your boiler is unable to start because the small ignition flame is not lighting, which is preventing the main burner from firing up.
Full guide for 25on the Ideal Classic RS
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