How much does it cost to fix boiler error code 34:0?

Typical repair cost for the boiler 34:0 fault is £80-180 including labour.

34:0 Low

Boiler Fault Code 34:0

Also written as 340 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 34:0 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is receiving a constant request for heat from an external control or thermostat, causing all the pumps to run continuously. (As reported on Viessmann Vitodens 200)

Pick your boiler brand for the 34:0 fix

Viessmann 34:0 6 models

Source

Information for the 34:0 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