BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the burner failed to light or stay lit during its startup sequence.
Check that you have fuel in your oil tankEnsure the oil supply valve is fully openPress the illuminated red reset button once to see if the burner restarts
Your boiler has tried to start several times but keep losing its flame, so it has locked itself for safety reasons.
Check that you have enough heating oil in your storage tankEnsure the oil supply valves are fully openPress the burner reset button once (if the fault persists, call a professional)
Your boiler has switched itself off because it has become too hot internally, likely due to a blockage or a pump issue stopping the water from moving.
Check that all radiator valves are fully open and there is no air trapped in the systemEnsure the system pressure is between 1 and 1.5 bar on the pressure gaugeOnce the boiler has cooled down, locate and press the manual reset button on the overheat thermostat behind the front casing
Your boiler's safety system is detecting a flame when there shouldn't be one, preventing it from starting up correctly.
Full guide for Burner reset light green/red alternate flash (0.5s)Your boiler has stopped working because it cannot detect a stable electrical connection from the mains power supply.
Full guide for Burner reset light orange steadyYour boiler has detected an unstable electrical supply, meaning the power entering the unit is either too high or too low for it to operate safely.
Full guide for Burner reset light orange/green fast flash (0.2s)on the Grant Vortex Blue
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 Grant 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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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