BoilerFaultCodesTechnical description
Whilst venting is in progress (constant temperature control unit)
What causes this fault?
This code appears when the boiler detects air pockets within its internal heat exchanger or the wider pipework. It physically triggers an automated venting sequence to push these bubbles out of the system, which helps prevent noisy operation and ensures efficient heat transfer. This usually happens after the system has been drained, refilled, or when new water has been added to the radiators.
This is most common in autumn when homeowners bleed their radiators or top up the system pressure in preparation for the heating season.
DIY fix possible
Wait approximately 20 minutes for the automated venting process to completeCheck that the system water pressure is between 1.0 and 1.5 barThe code should disappear and be replaced by the normal temperature display once finished