How much does it cost to fix Baxi error code E.01 – .02?

Typical repair cost for the Baxi E.01 – .02 fault is £120-£280 including labour.

E.01 – .02 High

Baxi E.01 – .02 Fault Code

Q: What does the Baxi E.01 – .02 fault code mean?

Your boiler has detected that the water coming back from your radiators is hotter than the water leaving the boiler, which usually means water is flowing in the wrong direction or a sensor has developed a fault.

Also written as E0102 — same fault.

The Baxi E.01 – .02 fault code means: your boiler has detected that the water coming back from your radiators is hotter than the water leaving the boiler, which usually means water is flowing in the wrong direction or a sensor has developed a fault.. It appears on 24 Baxi models in our database.

Technical description: Temperature measured by return sensor greater than flow sensor.

What causes the Baxi E.01 – .02 fault?

This fault occurs when the boiler detects that the water returning from your radiators is hotter than the water it just sent out, which contradicts the laws of physics in a normal system. The most common reasons are a pump that has failed or is struggling to push water around, a blockage in the heat exchanger, or temperature sensors that have become uncalibrated and are giving false readings.

This issue often surfaces in autumn when the heating is turned on for the first time after summer, as internal pump components can seize during long periods of inactivity.

Typical repair cost £120-£280 (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 E.01 – .02 fault code

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

Source

Baxi E.01 – .02 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