Fan does not run at max speed High

Baxi Fan does not run at max speed Fault Code

Also written as FANDOESNOTRUNATMAXSPEED — same fault.

The Baxi Fan does not run at max speed fault code means: your boiler has detected that it has become too hot and has automatically shut down to prevent damage, causing it to stop heating your home and water.. 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: Go to section 'J' - Check if safety thermostat has been activated (overheat thermostat). Allow to cool and check continuity.
Typical repair cost £120-250 (including labour)

Engineer required

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

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Baxi models that show the Fan does not run at max speed fault code

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

Source

Baxi Fan does not run at max speed 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