How much does it cost to fix boiler error code ER 15?

Typical repair cost for the boiler ER 15 fault is £150-350 including labour.

ER 15 High

Boiler Fault Code ER 15

Also written as ER15 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code ER 15 appears across 3 boiler brands and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected that the water is getting much hotter than it should as it travels through the system, suggesting a blockage or a failure in how the water circulates. (As reported on Johnson Starley Warmcair DW)

Pick your boiler brand for the ER 15 fix

Ferroli ER 15 1 model Johnson Starley ER 15 1 model Vaillant ER 15 1 model

Source

Information for the ER 15 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