BoilerFaultCodesThe 5 most common faults
01
Burner Lock-out High DIY-safe
Your boiler has detected a problem and safely turned itself off to prevent damage or danger.
What to try first
Check your oil tank to ensure you haven't run out of fuel.Wait 2 minutes for the boiler to cool down.Press the illuminated reset button on the burner once.
02
Lock-out High Engineer
Your boiler has stopped working because the burner failed to ignite, so it has safely shut itself down to prevent fuel from building up.
Full guide for Lock-out03
Overheat thermostat High Engineer
Your boiler has automatically turned itself off because it detected that it is running hotter than it should be.
Full guide for Overheat thermostat04
10 Emergency Engineer
Your boiler is struggling to clear its exhaust gases properly, which can be dangerous and indicates a potential issue with your chimney or ventilation.
Full guide for 1005
12 Emergency Engineer
Your boiler is leaking combustion gases into your home, which is a serious safety hazard that requires immediate professional attention.
Full guide for 12on the Grant Euroflame
PhotocellIgnition electrodesOil nozzleControl boxIgnition ElectrodesOil Nozzle
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
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