Emergency
Group 2, 8 flashes on Worcester Bosch Greenstar CDi Compact

Your boiler has detected an internal overheating issue or a blocked exhaust and has shut itself off to prevent damage or safety hazards.

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

MAX safety thermostat activated. Flue gas thermostat overheat or APS activated

From this model's manual
Verified against the Greenstar 27 30 RiCompact ErP installation & service manual.
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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