133 High

Baxi 133 Fault Code

The Baxi 133 fault code means: your boiler has tried to ignite but failed to stay alight, which is often caused by a lack of gas supply or a blocked condensation pipe.. It appears on 17 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: Safety time to establish flame exceeded

What causes the Baxi 133 fault?

This fault occurs when the boiler's control system attempts to light the burner but cannot detect a stable flame. The most common reasons are a temporary interruption in the gas supply, an ignition electrode that is too dirty to spark, or a blockage in the pipe that carries away waste water.

This fault is particularly common during freezing winter temperatures, as the external condensation pipe can freeze solid and prevent the boiler from firing.

Typical repair cost £100-£350 (including labour)

DIY fix possible

Check that your gas supply is turned on and you have credit on your meter.During freezing weather, check if your external white plastic condensate pipe is frozen and thaw it with warm water.Press the Reset button for five seconds.

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Baxi models that show the 133 fault code

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

Source

Baxi 133 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 7 July 2026