High
Flash on Worcester Bosch CDi Classic

Your boiler is failing to light the flame needed to produce heat or hot water, causing it to lock itself out for safety.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

If the boiler fails to light the BLUE power indicator (M) and reset button (E) will flash alternately.

From this model's manual
Verified against the Worcester Bosch Cdi Classic 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 high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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