Boiler Fault Code A1.3

Also written as A13 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code A1.3 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning This code is simply confirming that your boiler's burner is currently running correctly and there is no actual fault with your heating system. (As reported on Grant Vortex Eco External Wall Hung)