BoilerFaultCodesTechnical description
Flame simulation: Check ionisation probe (distance 3 - 4 mm).
What causes this fault?
This fault occurs when the boiler's internal sensor detects a flame signal at a time when the burner should be completely off. The most common reason is a faulty or contaminated sensing probe that is sending an incorrect electrical signal to the main control board, though it can also be caused by moisture on the internal electronics. For safety, the boiler will immediately shut down to ensure that gas is not flowing when it shouldn't be.
This fault is more frequent during periods of high humidity or heavy rain, as internal dampness or moisture ingress can cause the sensitive electronics to misread electrical signals.
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.