A boiler may stop because of a control setting, loss of system pressure, an ignition problem, a failed component or an external supply issue. The display and symptoms help; guesswork inside the casing does not.
Safe things to observe
Note any fault code, warning light and pressure reading that is visible without opening the boiler. Check whether other gas appliances or electrical circuits appear affected only if it is safe to do so.
- Is both heating and hot water affected?
- Did the problem start after a power cut or control change?
- Does the boiler attempt to start, or stay silent?
- Is there a visible leak or unusual noise?
When to stop checking
Do not remove the casing, touch gas fittings or keep resetting a boiler that repeatedly locks out. If you smell gas or a carbon monoxide alarm sounds, leave the property and call the National Gas Emergency Service on 0800 111 999 from outside.
Information for an engineer
Share the exact model, fault code, pressure reading and sequence of events. Photos of the display may be useful when requested, but avoid photographing or approaching anything unsafe.