B, C, D, E & F neons flashing High

Baxi B, C, D, E & F neons flashing Fault Code

Also written as BCDEFNEONSFLASHING — same fault.

The Baxi B, C, D, E & F neons flashing fault code means: your boiler has detected a problem with how it moves air and exhaust gases through the system, causing it to shut down for safety.. It appears on 1 Baxi model 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: Air pressure switch failure; go to section D
Typical repair cost £120-£240 (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 B, C, D, E & F neons flashing fault code

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

Source

Baxi B, C, D, E & F neons flashing 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