How much does it cost to fix boiler error code 109?

Typical repair cost for the boiler 109 fault is £150-300 including labour.

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Boiler Fault Code 109

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 109 appears across 8 boiler brands and 31 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 get water moving through its internal system effectively before it tries to fire up, causing it to shut down for protection. (As reported on Potterton Promax Ultra Combi ErP)

Pick your boiler brand for the 109 fix

Ariston 109 6 models Atag 109 2 models Baxi 109 10 models ECA 109 1 model Main 109 2 models Navien 109 5 models Potterton 109 4 models Worcester Bosch 109 1 model

Source

Information for the 109 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 7 July 2026