BURNER indicator Slow flash High

Grant BURNER indicator Slow flash Fault Code

Also written as BURNERINDICATORSLOWFLASH — same fault.

The Grant BURNER indicator Slow flash fault code means: your boiler's electronic control centre is experiencing an internal fault and is no longer able to safely communicate with the burner to provide heating or hot water.. It appears on 6 Grant models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Slow flash (once every 2 seconds): Indicates a possible fault with the PCB (relay). Replace PCB.
Typical repair cost £250-400 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Grant models that show the BURNER indicator Slow flash fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Grant BURNER indicator Slow flash fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

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