BoilerFaultCodesThe 6 most common faults
Your boiler has safety-tripped and needs a manual restart to clear a temporary glitch or overheating issue.
Why it happens: This fault occurs when the boiler's internal safety sensors detect that the unit has become too hot or has failed to light correctly. The most common reasons are a temporary interruption in the gas supply, a build-up of internal heat due to a pump failure, or a worn-out component that can no longer detect the flame.
Turn the boiler temperature control knob to '0' (the off position).Wait for at least 30 seconds for the internal components to reset.Turn the knob back to your desired temperature setting and follow standard lighting procedures.
Your boiler has stopped working because it failed to light or stay lit when it was supposed to.
Why it happens: This fault occurs when the boiler's internal safety system cannot detect a flame after several attempts to ignite. The root cause is usually a lack of fuel reaching the burner, a worn-out ignition spark, or a sensor that has become too dirty to 'see' the flame even if it is actually lit.
Turn the temperature control knob to the 'Off' positionWait for at least 30 seconds for the unit to resetTurn the temperature control knob back to your desired settingEnsure there is gas reaching the property (check other gas appliances)
Your boiler has switched itself off because it has detected that the water inside has become dangerously hot.
Why it happens: This fault occurs when the internal temperature of the boiler exceeds safe limits, triggering a safety shut-off to protect the system. The most common reason is a lack of water flow, often caused by a failing circulation pump or a blockage in the heat exchanger preventing heat from being carried away. In some cases, it can also be triggered by a faulty sensor giving an incorrect high-temperature reading.
Wait for the boiler to cool down completely (at least 20-30 minutes).Locate the reset button, typically found behind the small drop-down door or on the underside of the boiler.Press the reset button firmly; if the neon light goes out and the boiler restarts, monitor it closely.Ensure all radiator valves are open and the pump is running to prevent it happening again.
Your boiler has switched itself off as a safety precaution because it has either detected a fault or has become too hot.
Why it happens: This fault occurs when the internal safety sensors detect that the water inside the unit has reached a dangerously high temperature or if the system has failed to ignite properly. The most common reason is a lack of water circulation, often caused by a failing pump or a blockage in the pipework that prevents heat from moving away from the boiler. It can also be triggered by a faulty control board incorrectly reading the system's temperature.
Locate the reset button on the control panel.Press and release the reset button to see if the boiler restarts.Check that your heating controls (thermostat) are calling for heat.Ensure your gas supply is active and hasn't been interrupted.
Your boiler has safety-tripped and simply needs a manual restart to try and fire up again.
Why it happens: This fault occurs when the boiler's internal safety sensors detect that the unit has become too hot or has failed to light after several attempts. The most common reasons are a temporary interruption in the gas supply, a build-up of debris on the ignition components, or a lack of water circulation preventing the heat from escaping the heat exchanger.
Turn the boiler temperature control knob to the '0' position.Wait for at least 30 seconds.Turn the control knob back to your desired temperature setting to restart the ignition sequence.
Your boiler has switched itself off because it has either gotten too hot or it failed to light the flame correctly.
Why it happens: This fault happens when either the boiler’s internal temperature has exceeded safe limits or the burner has failed to light after several attempts. It is often triggered by a lack of water flow preventing heat from leaving the boiler, or an issue with the electrical spark that starts the flame.
Check that your gas supply is turned on at the meterEnsure all radiator valves are open and there is water in the systemPress the reset button on the front control panel to see if the boiler restarts
on the Glow-worm Hideaway 100
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 Glow-worm 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