H2
Ideal Flow Thermistor / Temperature Sensor Fault

Ideal boiler displays H2 and may shut down intermittently

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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

Faulty flow NTC thermistor, Loose sensor connection, Damaged sensor wiring, PCB reading error

How to Fix / Troubleshooting

Safety first: Turn off the boiler and allow it to cool before any inspection. Do not remove the boiler case.

User checks:

  • Reset: Power cycle the boiler and reset once to see if the fault clears.

Engineer tasks: Measure resistance of the flow thermistor, check wiring back to the PCB, and replace the flow NTC sensor if out of specification. Replace PCB if sensor and wiring are sound but fault remains.

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Repair Difficulty

Hard 4/5

Required Part

Flow NTC Thermistor
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