04
Immergas
Gas Valve Control / Internal Gas Valve Fault
Boiler displays error 04, no ignition, sometimes accompanied by humming from gas valve area.
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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
Defective gas valve coil, Loose or damaged gas valve wiring harness, Faulty control PCB gas valve driver, Incorrect gas valve adjustment
How to Fix / Troubleshooting
Critical safety: Gas valve testing and replacement must only be performed by a licensed gas technician. Do not attempt to adjust gas pressures without proper equipment and training.
- Reset and observe: Reset the boiler and listen for the gas valve click during ignition. If there is no click, proceed with checks.
- Check wiring: With power isolated, inspect the gas valve connector and harness for loose pins, corrosion, or damage. Reseat the connector firmly.
- Measure coil resistance (engineer): Using a multimeter, measure the resistance of the gas valve coils and compare with Immergas specifications. Replace the gas valve if readings are out of range or coils are open circuit.
- Check PCB output: Verify that the control board supplies the correct voltage to the gas valve during ignition. If no voltage is present and wiring is sound, the PCB may be faulty and require replacement.
- Commissioning after replacement: After fitting a new gas valve, set inlet and burner pressures according to the Immergas data plate and combustion analysis. Perform a full tightness test and flue gas analysis.
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Repair Difficulty
Professional Required
5/5
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