Smell gas? Stop. Don't touch electrical switches or use naked flames. Open doors and windows, turn the gas off at the meter if you can do it safely, leave the property and call the National Gas Emergency Service on 0800 111 999.
Checks you can do yourself
- Pressure. If the gauge is below about 1 bar, the boiler may shut down. How to top up pressure.
- Frozen condensate pipe. In freezing weather, a blocked condensate pipe makes the boiler stop and show a fault. How to thaw it.
- The thermostat. If your room thermostat is wireless, change its batteries. If it's somewhere warm, such as near a radiator, a sunny window or the kitchen, it may be turning the heating off too early.
- Radiator valves. If most radiators are turned off, the boiler can overheat and switch itself off. Open a few more valves.
- Gas supply. If you have a prepayment meter, check it has credit. Check your gas hob still lights.
- Fault codes. If the display shows a code, look it up in your manual or our boiler help guides.
When to call an engineer
If none of those explain it, the cause is likely inside the boiler: for example the pump, a sensor, the fan, a blocked heat exchanger or the circuit board. These all need a Gas Safe registered engineer. Switching on and off very frequently, sometimes called short cycling, wastes energy and wears the boiler, so it's worth getting looked at even if the heating mostly works.
Never take the casing off your boiler or try to repair gas parts yourself. That work must be done by a Gas Safe registered engineer. With boiler cover, your provider sends one for you. Compare boiler cover.
Have boiler cover?
Call your provider before paying an engineer yourself. A repair like this is exactly what cover is for.
No cover yet? A new plan won't pay for a fault you already have, because problems that exist when you join aren't covered and there's a waiting period at the start. It can protect you next time.
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Last updated 30 October 2026