BoilerFaultCodes 318 / E9 High
Boiler Fault Code 318 / E9
Also written as 318E9 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 318 / E9 appears across 1 boiler brand 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 a key safety sensor measuring temperature inside the flue is currently not sending a signal, causing the boiler to shut down to prevent overheating. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the 318 / E9 fix
Source
Information for the 318 / E9 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