How much does it cost to fix boiler error code D.33?

Typical repair cost for the boiler D.33 fault is £180-450 including labour.

D.33 Medium

Boiler Fault Code D.33

Also written as D33 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code D.33 appears across 3 boiler brands and 41 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to match the correct fan speed needed to safely clear exhaust gases, which may lead to the system pausing for safety. (As reported on Vaillant ecoTEC)

Pick your boiler brand for the D.33 fix

Glow-worm D.33 6 models Heatline D.33 7 models Vaillant D.33 28 models

Source

Information for the D.33 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