BoilerFaultCodesThe 3 most common faults
Your boiler has stopped trying to light itself because the small starter flame failed to ignite within the safety time limit.
Why it happens: This fault occurs when the boiler's internal safety system detects that the small pilot flame hasn't lit correctly. The most common reasons are a build-up of debris on the ignition part or air trapped in the gas supply, which prevents the spark from catching. If the boiler cannot confirm a healthy flame within 60 seconds, it shuts down to prevent unburnt gas from escaping.
Locate the reset button or turn the control knob to the 'Reset' position.Hold for 5 seconds and release.If the fault persists after three attempts, contact a Gas Safe engineer to clear air from the gas line.
Your boiler has switched itself off because it has gotten too hot, likely due to a circulation problem or a temporary blockage.
Why it happens: This fault occurs when the water inside the heat exchanger reaches a dangerously high temperature, triggering a safety shut-off. The most common reasons are a failing pump that isn't moving water away from the boiler quickly enough or a buildup of debris and sludge that is restricting the flow. Essentially, the boiler is generating heat but has no way to vent it into your radiators.
Ensure all radiator valves are fully open and there is no air in the system.Allow the boiler to cool down completely for at least 20 minutes.Locate the manual reset button (usually behind the front flap or underneath) and press it firmly to clear the red light.
Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.
Full guide for Overheat (Red LED)on the Potterton Housewarmer
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 Potterton 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