Boiler Fault Code Pulsation on start

Also written as PULSATIONONSTART — same fault.

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

Fault code Pulsation on start appears across 1 boiler brand and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to ignite smoothly because the air and fuel mixture is incorrect or there is a blockage in the flue, causing it to shudder when it starts up. (As reported on Worcester Bosch Utility)