BoilerFaultCodesTechnical description
Not available
What causes this fault?
This occurs when the boiler detects potential air pockets within the internal pipework or heat exchanger, often following a recent repair or after the system has been refilled. To prevent damage from overheating, the boiler automatically runs a five-minute venting cycle to push any trapped bubbles out through the automatic air vent. It is a protective measure rather than a breakdown, ensuring the system is primed and safe to fire up.
This is more common in autumn when homeowners top up their system pressure or bleed radiators for the first time after the summer break.
DIY fix possible
Wait for the program to finish, as it usually stops automatically after 5 to 10 minutesEnsure all radiator valves are fully open to help move air through the systemCheck the boiler pressure gauge and top it up to 1.5 bar if it has dropped