BoilerFaultCodesTechnical description
Ignition lockout, Overheat lockout, Internal error (reset lockout by gently pressing reset button for 5 seconds). Common causes: No gas or low gas pressure, Weak spark or spark not across elecrodes, Gas valve leaking or failed, Low water pressure or boiler dry, Pump fail, Primary sensor position, Flame sensor fail or connector, Overheat stat tripped or disconnected or faulty, Blocked burner, Blocked heat exchanger, Faulty harness, Board fault.
What causes this fault?
This fault occurs when the boiler tries to light but fails to detect a flame, or if the internal temperature becomes unsafely high. It is often caused by a lack of fuel reaching the burner, a worn-out ignition spark, or a pump failure that prevents water from moving, leading to immediate overheating.
This issue often surfaces during the first cold snap of autumn when the pump or gas valve seizes up after being inactive over the summer.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.