E109 High

Baxi E109 Fault Code

The Baxi E109 fault code means: your boiler is struggling to move heated water through the system, causing it to shut down to prevent overheating.. It appears on 28 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: Poor circulation

What causes the Baxi E109 fault?

This fault occurs when the water inside your boiler gets too hot too quickly because it isn't being pushed around your radiators fast enough. The most common reasons are a pump that has seized up or a build-up of sludge and debris that is physically blocking the pipework. Because the heat has nowhere to go, the boiler forces a shutdown to protect its internal components from heat damage.

This issue often surfaces in autumn when the heating is turned back on for the first time, as internal pump parts can seize up after sitting idle during the summer months.

Typical repair cost £100-£350 (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 openBleed your radiators to remove any trapped air pockets

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Baxi models that show the E109 fault code

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

Source

Baxi E109 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