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 11 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 31 August 2026