Emergency
FA on Worcester Bosch 537i

Your boiler has detected a flame even though it has commanded the gas supply to turn off, which means it cannot safely control the combustion process.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

What the manual says

Manufacturer manual

Flame still present after gas has been cut off

From this model's manual
Verified against the Worcester Bosch 537i installation & service manual, page 46.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the boiler's internal sensors continue to detect a flame even after the system has commanded the gas to stop flowing. The most common reasons are a gas valve that is physically stuck open or failing to seal correctly, or a faulty sensor providing a false signal to the control board.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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