Emergency
AL 96 on Sime Murelle Pro HE System R

Your boiler has shut down because the exhaust pipe is blocked or restricted, preventing harmful waste gases from leaving your home safely.

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

Lockout due to flue (exhaust) blockage / smoke outlet clogged — inspect and clear flue system

From this model's manual
Verified against the Sime Murelle Pro He System R installation & service manual, page 33.
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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