BoilerFaultCodesYour boiler has detected a flame when there shouldn't be one, which means the safety system has locked the unit down to prevent an unsafe situation.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Warm start sensor interruption (ecomax 800) / False light (flame signal present but gas valve closed)
What causes this fault?
This fault occurs when the boiler's sensors detect a flame signal even though the gas valve should be closed and the burner turned off. The most common reason is a faulty ionisation probe sending a false electrical signal to the control board, or a gas valve that is slightly leaking or failing to close fully. In some cases, moisture on the internal electronics or a failing circuit board can also trick the system into thinking a flame is present.
This fault can sometimes be more frequent during periods of high humidity or heavy rain, as moisture ingress can affect the sensitive electrical signals between the probe and the control board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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