BoilerFaultCodes 318 High
Boiler Fault Code 318
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 318 appears across 1 boiler brand and 4 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 sensor responsible for monitoring the exhaust gases has become unplugged or has a loose connection, preventing it from operating safely. (As reported on Worcester Bosch 24/28/35 CDi MkII)
Pick your boiler brand for the 318 fix
Source
Information for the 318 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