Slow flashes Emergency

Worcester Bosch Slow flashes Fault Code

Also written as SLOWFLASHES — same fault.

The Worcester Bosch Slow flashes fault code means: your boiler is still sensing a flame even though it has tried to shut off the gas, which is a safety concern that requires a professional inspection.. It appears on 1 Worcester Bosch model in our database.

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: Flame detected after gas shut off. Check gas valve and wiring to gas valve. Clean condensation trap and check electrode assembly. Flue clear?
Typical repair cost £180-£450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Worcester Bosch models that show the Slow flashes fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch Slow flashes fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026