502
Ariston
False Flame Detection
Error 502, flame detected when there should be none (before ignition or after shutdown).
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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
Shorted ionization electrode to ground, Moisture bridging electrode, Control board flame circuit fault, Incorrect wiring polarity
How to Fix / Troubleshooting
Safety: Do not operate the furnace if it indicates flame when off; this is a safety-critical fault.
- Check mains polarity: Ensure live and neutral are correctly connected at the furnace terminal block according to Ariston wiring diagram.
- Inspect ionization electrode: Remove and check for cracks, carbon tracking, or moisture. Clean and dry thoroughly or replace if damaged.
- Inspect wiring harness: Look for damaged insulation or wires touching the burner or chassis.
- Reset and test: After corrections, reset the unit. If 502 persists, the control board likely needs replacement.
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Repair Difficulty
Hard
4/5
Required Part
Control Board (PCB)
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