How much does it cost to fix Baxi error code 128?

Typical repair cost for the Baxi 128 fault is £100-£350 including labour.

128 High

Baxi 128 Fault Code

Q: What does the Baxi 128 fault code mean?

Your boiler started to heat up but the flame went out unexpectedly while it was running.

The Baxi 128 fault code means: your boiler started to heat up but the flame went out unexpectedly while it was running.. It appears on 26 Baxi models in our database.

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 £100-£350 (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 27 April 2026