BoilerFaultCodesThe 6 most common faults
The boiler appears to have no power at all, so it isn't producing heating or hot water, but this is usually caused by a switch, fuse or power supply issue that can often be checked safely.
Check that the boiler's on/off switch is turned on and that the power switch on the wall (fused spur) is switched on with its fuse intact.Check your consumer unit (fuse box) to see whether the circuit for the boiler has tripped, and reset it if so.Check that the room thermostat or timer is not switching the boiler off, and replace its batteries if it has any.If the boiler still shows no display after these checks, stop and call a Gas Safe registered engineer, as the fault is likely inside the boiler's electrical circuit.
Your boiler has shut itself down as a safety precaution, most often because it is low on water, so it needs a quick check before it can heat your home again.
Check the boiler's pressure gauge with the boiler cold. A reading below 1 bar usually means the system is low on water.If the pressure is low, top it up using the filling loop, following the boiler manual, and watch the gauge until it reaches about 1.5 bar.Close the filling loop, then press the reset button and see whether the boiler restarts.If the code returns, or the pressure keeps dropping, stop and call a Gas Safe registered engineer, as this may point to a leak or a faulty pump or flow switch.
The boiler has stopped trying to light after several failed attempts, so it has shut itself down as a safety precaution and will need to be reset and checked.
Full guide for On Off OnYour boiler has switched itself off to protect itself because it got too hot, and it will need a reset once it has cooled down and the cause has been checked.
Full guide for Flash Off OnYour boiler has shut itself down for safety because a part that moves air through it isn't working correctly, so it won't provide heating or hot water until a qualified engineer has looked at it.
Full guide for Flash Flash OnYour boiler is showing a temperature sensor fault, which usually means it can't read the water temperature correctly and may stop heating or switch itself off as a safety precaution.
Full guide for On Flash Onon the Potterton Precision
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