How much does it cost to fix Baxi error code E.01 – .20?

Typical repair cost for the Baxi E.01 – .20 fault is £120-350 including labour.

E.01 – .20 High

Baxi E.01 – .20 Fault Code

Q: What does the Baxi E.01 – .20 fault code mean?

Your boiler has switched itself off because it has become too hot inside, likely due to water not flowing correctly or a faulty internal sensor.

Also written as E0120 — same fault.

The Baxi E.01 – .20 fault code means: your boiler has switched itself off because it has become too hot inside, likely due to water not flowing correctly or a faulty internal sensor.. It appears on 24 Baxi models in our database.

Technical description: Maximum flue gas temperature reached. No circulation or sensor fault.

What causes the Baxi E.01 – .20 fault?

This fault occurs when the internal temperature of the boiler rises dangerously high, triggering a safety shut-off to prevent damage. The most common reason is that water isn't moving through the system quickly enough to carry heat away, often due to a pump failure or a blockage. It can also be caused by a build-up of debris inside the heat exchanger that prevents efficient heat transfer.

Typical repair cost £120-350 (including labour)

DIY fix possible

Check that your home's radiator valves are fully openEnsure your system pressure is between 1 and 1.5 bar on the pressure gaugeTry resetting the boiler by turning the selector switch to 'R' for five seconds

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Baxi models that show the E.01 – .20 fault code

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

Source

Baxi E.01 – .20 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