5 flashes red High

Baxi 5 flashes red Fault Code

Also written as 5FLASHESRED — same fault.

The Baxi 5 flashes red fault code means: your boiler's internal computer is having difficulty communicating with its main control unit, meaning it cannot process the settings needed to run safely.. It appears on 4 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: Parameter fault: Bad connection to PU, Parameter error or faulty PU
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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Baxi models that show the 5 flashes red fault code

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

Source

Baxi 5 flashes red 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