4 Red Flashes High

Baxi 4 Red Flashes Fault Code

Also written as 4REDFLASHES — same fault.

The Baxi 4 Red Flashes fault code means: your boiler has detected an issue with the ventilation fan, which means it cannot safely clear exhaust fumes and will not ignite.. It appears on 27 Baxi models in our database.

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.

Technical description: Fan Fault

What causes the Baxi 4 Red Flashes fault?

This fault occurs when the boiler's control system senses that the fan is not spinning at the correct speed to safely expel waste gases. The most common reasons are a mechanical failure of the fan motor itself, a loose connection in the wiring, or a fault on the main circuit board that prevents power from reaching the fan.

Typical repair cost £220-450 (including labour)

Engineer required

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

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Baxi models that show the 4 Red Flashes fault code

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

Source

Baxi 4 Red Flashes fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.

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