BoilerFaultCodes D1 240 High
Boiler Fault Code D1 240
Also written as D1240 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D1 240 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has stopped working because it is unable to accurately measure the temperature of the water returning from your radiators due to a faulty sensor signal. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the D1 240 fix
Source
Information for the D1 240 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