How much does it cost to fix boiler error code 90:128?

Typical repair cost for the boiler 90:128 fault is £120-220 including labour.

90:128 Low

Boiler Fault Code 90:128

Also written as 90128 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 90:128 appears across 1 boiler brand and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's outside temperature sensor has failed or is giving an incorrect reading, meaning the system may not heat your home efficiently based on the weather. (As reported on Viessmann Vitodens 300-W)

Pick your boiler brand for the 90:128 fix

Viessmann 90:128 5 models

Source

Information for the 90:128 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