BoilerFaultCodesThe 6 most common faults
Your boiler has stopped because it failed to ignite, so you need to perform a simple reset to try and wake it up again.
Ensure your heating oil tank has sufficient fuelWait 45 seconds for the boiler to cycle internallyPress the illuminated red reset button once to restart the burner
Your boiler has stopped working because the water pressure in your heating system has dropped too low to operate safely.
Locate the filling loop (usually a flexible silver hose) under the boiler or in the airing cupboard.Open the small valve black handles slowly until you hear water entering the system.Watch the pressure gauge and close the valves when it reaches 1.5 bar, then press the reset button on the control panel.
Your boiler has switched itself off because it has reached an internal temperature that is too high, preventing potential damage or safety issues.
Wait for the boiler to cool down completely (at least 20-30 minutes).Locate the overheat reset button under the screw-on cap on the control panel.Press the button firmly until you hear a click, then restart the boiler.
Your boiler has become too hot and has automatically shut itself down to prevent damage or safety issues.
Identify the black reset button cover on the control panelUnscrew the cover and firmly press the small reset button underneath until it clicksEnsure your radiator valves are open and the system pressure is correct
Your boiler has detected that the water pressure in the system is too low to run safely and has switched itself off to prevent damage.
Locate the filling loop (a flexible silver hose) usually found under the boiler or near the hot water cylinder.Open the small black valves slowly until you hear water entering the system.Watch the pressure gauge and close the valves once the needle reaches between 1 and 1.5 bar.
Your boiler has shut itself down because it became too hot, acting as a safety precaution to prevent damage.
Locate the reset button on the control panel, which may be hidden behind a small screw-off plastic cap.Ensure all radiator valves are open and the system pressure is between 1 and 1.5 bar on the gauge.Press the reset button firmly; if the boiler restarts and runs, monitor it, but call a technician if it happens again.
on the Grant Outdoor Combi 90 Mkii
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