A02
Hoval
Gas Valve or Gas Train Fault
Boiler attempts to start, fan runs briefly, then locks out with A02, no flame established
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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, Gas valve not receiving control signal from PCB, Blocked gas filter in gas train, Incorrect gas pressure at boiler inlet
How to Fix / Troubleshooting
Warning: Gas train work must be carried out by a licensed gas technician. Do not open or adjust the gas valve yourself.
- Check gas isolation valves: Confirm all gas cocks on the Hoval boiler gas train are fully open.
- Verify inlet pressure (technician only): Using a manometer on the test point, confirm that the inlet gas pressure meets the value specified on the Hoval boiler data plate.
- Inspect wiring: With power off, check the gas valve connector for secure fit and no corrosion or burn marks. Trace the harness back to the main control PCB.
- Gas filter: Many Hoval boilers have a gas filter upstream of the valve. A technician should isolate, depressurise, and clean/replace this filter if blocked.
- If A02 persists after basic checks, do not operate the boiler. Arrange a Hoval-authorised service visit to test the gas valve coil resistance and replace the valve if faulty.
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Repair Difficulty
Professional Required
5/5
Required Part
Gas Valve Assembly
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