How much does it cost to fix boiler error code J6-20?

Typical repair cost for the boiler J6-20 fault is £120-280 including labour.

J6-20 High

Boiler Fault Code J6-20

Also written as J620 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code J6-20 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 has detected that the water returning to the unit is too hot, which has caused it to shut down to prevent damage. (As reported on Daikin D2CND)

Pick your boiler brand for the J6-20 fix

Daikin J6-20 1 model

Source

Information for the J6-20 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