BoilerFaultCodes dE Medium
Boiler Fault Code dE
Also written as DE — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code dE appears across 1 boiler brand and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has lost connection with the temperature sensor that controls your second heating zone, meaning it cannot properly regulate the temperature for that part of your home. (As reported on Viessmann Vitodens 200)
Pick your boiler brand for the dE fix
Source
Information for the dE 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