How much does it cost to fix Baxi error code Lights On Flash On?

Typical repair cost for the Baxi Lights On Flash On fault is £90-160 including labour.

Lights On Flash On High

Baxi Lights On Flash On Fault Code

Q: What does the Baxi Lights On Flash On fault code mean?

Your boiler has detected a problem with its internal temperature sensor, meaning it cannot accurately tell how hot the water is and has shut down as a safety precaution.

Also written as LIGHTSONFLASHON — same fault.

The Baxi Lights On Flash On fault code means: your boiler has detected a problem with its internal temperature sensor, meaning it cannot accurately tell how hot the water is and has shut down as a safety precaution.. It appears on 3 Baxi models in our database.

Technical description: Thermistor section: Unplug thermistor, check resistance between 0.5kO & 20kO.

Typical repair cost £90-160 (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 Lights On Flash On fault code

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

Source

Baxi Lights On Flash On 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