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

Typical repair cost for the boiler HL fault is £120-280 including labour.

HL High

Boiler Fault Code HL

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code HL appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has overheated, causing a safety sensor to automatically shut the system down to prevent damage. (As reported on Unical Alkon R 28 HE)

Pick your boiler brand for the HL fix

Unical HL 2 models

Source

Information for the HL 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