BoilerFaultCodesTechnical description
Internal boiler wiring integrity issue or deteriorated electrode causing flame signal before gas valve activation.
What causes this fault?
This fault occurs when the boiler's control system detects an electrical current that mimics a flame before the gas valve has even opened. The most common reason is a buildup of carbon or moisture on the sensing electrode that allows electricity to 'leak', or a fault within the main circuit board that is misreading signals. Because the boiler thinks a flame is already present, it shuts down immediately as a safety precaution to prevent gas from being released incorrectly.
This issue can be more common during periods of high humidity or very cold weather, as moisture or condensation inside the boiler casing can interfere with the sensitive electrical signals of the ignition system.
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.