Boiler Fault Code Error 20

Also written as ERROR20 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code Error 20 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 lost the ability to accurately measure the temperature of the water, so it has safely shut itself down to prevent overheating. (As reported on Potterton Titanium)