E109 High

Boiler Fault Code E109

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code E109 appears across 4 boiler brands and 38 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to move water around the system before it starts the heating process, which is often caused by a blockage or a pump issue. (As reported on Main Eco Compact)

Pick your boiler brand for the E109 fix

Baxi E109 28 models Main E109 1 model Navien E109 7 models Potterton E109 2 models

Source

Information for the E109 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026