How much does it cost to fix boiler error code A5?

Typical repair cost for the boiler A5 fault is £100-£180 including labour.

A5 High

Boiler Fault Code A5

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code A5 appears across 3 boiler brands and 27 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's temperature sensor responsible for monitoring the hot water storage is faulty or has lost connection, meaning the system cannot safely heat your water. (As reported on Worcester Bosch Greenstar CDi Compact)

Pick your boiler brand for the A5 fix

Atag A5 2 models Viessmann A5 12 models Worcester Bosch A5 13 models

Source

Information for the A5 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