10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Vortex Blue
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
Tap any card for details
Your boiler is struggling to establish a steady flame when it first turns on, usually because it isn't getting quite enough air or fuel to start smoothly.
Your boiler has temporarily shut down because the internal safety thermostat detected that it was getting too hot.
Your oil boiler is failing to start up because it is not receiving power or fuel, or the burner itself is not firing.
Your boiler has detected a temporary issue with the burner and has safely shut itself down to prevent any damage.
Your boiler is making a rumbling or pulsing sound because the burner is not getting the right balance of air and fuel to burn smoothly.
Your boiler is leaking exhaust gases into the room, which poses a serious carbon monoxide risk and requires immediate professional attention.
Your boiler is struggling to breathe properly when it tries to start up, which can cause smoke, soot, or a puffing sound.
Your Grant boiler is letting out an oil smell, which usually means there is a small leak somewhere in the fuel supply pipework.
Your boiler is producing visible smoke from the flue, which means the fuel is not burning cleanly and needs immediate professional attention.
Your Grant oil boiler is failing to reach the proper temperature because it is either not burning fuel efficiently or having trouble retaining the heat.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes