AL22
FG Wilson
Coolant Temperature Signal Error
Controller shows AL22 – Coolant Temperature Sensor Fault
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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
Open or shorted coolant temperature sensor, Broken wiring to sensor, Incorrect sensor type fitted, Faulty controller analog input
How to Fix / Troubleshooting
Safety first: Stop the generator and isolate battery negative. Allow engine to cool before touching the sensor area.
- Locate sensor: Find the coolant temperature sensor on the thermostat housing or cylinder head.
- Inspect wiring: Check the harness for damage and the connector for corrosion. Clean and reseat the connector.
- Basic sensor test: With a multimeter, measure resistance across the sensor terminals and compare with engine manual values at ambient temperature. Infinite or zero resistance indicates a fault.
- Replace sensor: If faulty, drain a small amount of coolant if necessary, remove the sensor, and install a new one with thread sealant as specified.
- Retest: Refill coolant if needed, clear the alarm, and run the generator while monitoring temperature readings.
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Repair Difficulty
Medium
3/5
Required Part
Coolant Temperature Sensor
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