128 High

Baxi 128 Fault Code

The Baxi 128 fault code means: your boiler has attempted to start but failed to detect a flame, causing it to stop operating to ensure your safety.. It appears on 25 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: Loss of flame during operation

What causes the Baxi 128 fault?

This fault occurs when the boiler successfully lights, but the internal sensors lose track of the flame while it is running, causing the system to shut down for safety. The most common reasons are a worn-out sensing probe that can no longer 'see' the fire, or an unstable gas supply that prevents the flame from staying consistent.

Typical repair cost £120-250 (including labour)

DIY fix possible

Check that your gas pre-pay meter has creditEnsure other gas appliances in your home are working to confirm gas supplyPress the 'Reset' button for five seconds

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Baxi models that show the 128 fault code

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

Source

Baxi 128 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