BoilerFaultCodes 240 / D1 High
Boiler Fault Code 240 / D1
Also written as 240D1 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 240 / D1 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 detected a faulty reading from a temperature sensor that monitors the water returning to the system, causing it to shut down for safety. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the 240 / D1 fix
Source
Information for the 240 / D1 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