E.04 – .08 High

Baxi E.04 – .08 Fault Code

Also written as E0408 — same fault.

The Baxi E.04 – .08 fault code means: your boiler has shut down because it has detected it is getting too hot, likely due to a lack of water flow or a sensor failure.. It appears on 24 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: Permanent fault. Maximum safe temperature value reached, safety thermostat open-circuited, no circulation, sensor not or badly connected, bad connection or sensor fault.

What causes the Baxi E.04 – .08 fault?

This fault occurs when the boiler's internal water temperature exceeds a safe limit, causing the system to shut down to prevent damage. The most common reasons are a lack of water circulation caused by a failed pump, a blockage in the heat exchanger, or a faulty sensor providing an incorrect temperature reading.

This issue often surfaces when the heating is first turned on in autumn, as internal pumps can seize up after being idle throughout the summer.

Typical repair cost £90-250 (including labour)

DIY fix possible

Check that the boiler pressure is between 1.0 and 1.5 bar on the gaugeEnsure all radiator valves are fully open to allow water circulationPerform a reset by turning the selector knob to the 'R' position for five seconds

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Baxi models that show the E.04 – .08 fault code

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

Source

Baxi E.04 – .08 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