Emergency
100mm on Main Combi 24

Your boiler has detected that the flue pipe is set to the wrong size or is incorrectly configured for your specific model, which prevents it from safely venting exhaust gases.

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

Flue Terminal Diameter

From this model's manual
Verified against the Main Combi 24 installation & service manual, page 9.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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Related fault codes

E119View →E110View →

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