How much does it cost to fix boiler error code 738?

Typical repair cost for the boiler 738 fault is £90-150 including labour.

738 Low

Boiler Fault Code 738

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 738 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is connected to a smart heating control that hasn't been set up correctly in the system settings yet, so it is just waiting for the right instructions. (As reported on Viessmann Vitodens 100-W B1GA)

Pick your boiler brand for the 738 fix

Viessmann 738 1 model

Source

Information for the 738 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