A/C Evaporator Temperature Sensor Circuit Intermittent

Where it lives

For P0539, the sensor sits on the circuit this code reports. The description of P0539 reports a fault at the sensor.

Check these first

• A failing evaporator temperature sensor
• Corrosion or water in the sensor connector
• A chafed wire making intermittent contact
• A loose sensor mount
• A fluctuating refrigerant charge

What to do next

1. Watch evaporator temperature data while moving the harness
2. Inspect the connector for water or corrosion
3. Check the sensor mount and wiring for chafing
4. Verify the refrigerant charge is steady
5. Replace the sensor if the signal cuts in and out
6. Clear the code and retest

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