BoilerFaultCodes 75 mm Emergency
Boiler Fault Code 75 mm
Also written as 75MM — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 75 mm appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is reporting a physical blockage or debris issue in the flue or drainage pipes, which is preventing it from venting exhaust gases safely. (As reported on Malvern TenTwenty)
Pick your boiler brand for the 75 mm fix
Source
Information for the 75 mm 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