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's fan is not spinning or communicating correctly with the system, preventing the boiler from starting safely.. It appears on 22 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 detects that the fan is not spinning at the required speed to safely clear exhaust gases. The most common reasons are a mechanical failure of the fan motor, a buildup of debris blocking the blades, or a communication error caused by a faulty circuit board.

Typical repair cost £250-£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 7 July 2026