Emergency
Yellow L.E.D. H on Ariston Microsystem 15

Your boiler has temporarily stopped because it is detecting a problem with safely venting the exhaust gases outside.

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.

Technical description

Temporary shutdown due to defective discharge of exhaust products

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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