How much does it cost to fix Grant error code CH PUMP Fast flash?

Typical repair cost for the Grant CH PUMP Fast flash fault is £120-200 including labour.

CH PUMP Fast flash High

Grant CH PUMP Fast flash Fault Code

Q: What does the Grant CH PUMP Fast flash fault code mean?

Your boiler's temperature sensor is disconnected or faulty, meaning it cannot accurately track the heat of the water and has stopped your heating from working.

Also written as CHPUMPFASTFLASH — same fault.

The Grant CH PUMP Fast flash fault code means: your boiler's temperature sensor is disconnected or faulty, meaning it cannot accurately track the heat of the water and has stopped your heating from working.. It appears on 5 Grant models in our database.

Technical description: Check CH ‘flow’ thermistor connection to the PCB. Replace ‘flow’ thermistor.

Typical repair cost £120-200 (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 CH PUMP Fast flash fault code

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

Source

Grant CH PUMP Fast 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 27 April 2026