Boiler Fault Code 16-64

Also written as 1664 — same fault.

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

Fault code 16-64 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 shut down because the exhaust gases are getting too hot, indicating a potential blockage or safety issue in the flue pipe. (As reported on Daikin D2CND)