51
Intergas
Pump Overrun Control Fault
Boiler displays error code 51, pump runs continuously even with no demand
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Stuck pump relay on PCB, Incorrect wiring from external controls, Faulty flow sensor indicating false demand, PCB fault
How to Fix / Troubleshooting
Warning: Continuous pump running wastes energy and may indicate a control fault. Internal checks must be done by an engineer.
- Check controls: Ensure all heating and hot water demands are off (thermostats turned down, programmer off). If the pump still runs, the issue is internal.
- Power cycle: Turn off power at the fused spur for 30 seconds, then restore. If the pump immediately starts again with no demand, the PCB relay may be stuck.
- Engineer tasks: The engineer will test the pump control output, check for false demand signals from sensors, and replace the PCB if the relay is welded closed.
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Repair Difficulty
Hard
4/5
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