A/C Evaporator Temperature Sensor Circuit Intermittent

What it means

P0539 is stored when the A/C Evaporator Temperature signal drops out or jumps erratically for short periods. Intermittent faults are almost always connector, wiring or vibration related.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

Symptoms

• Check engine light on
• Idle too high, too low or hunting
• Stalling when coming to a stop
• Speedometer or cruise control not working in some cases

Common causes

1. Damaged, chafed or corroded wiring in the A/C Evaporator Temperature circuit
2. Corroded, loose or water-damaged connector terminals
3. Failed A/C Evaporator Temperature component (sensor, solenoid or actuator)
4. Poor ground connection for the module or component
5. Faulty control module driver (rare, confirm all else first)

How to diagnose

1. Read freeze frame data and note when the code set (cold start, under load, after rain)
2. Inspect the A/C Evaporator Temperature connector for bent pins, corrosion and water; wiggle the harness with the engine running and watch live data
3. Measure supply voltage and ground at the connector with the key on
4. Check the signal wire for shorts to ground or battery and for continuity to the control module
5. Test or substitute the A/C Evaporator Temperature only after wiring and connectors are confirmed good
6. Clear the code and complete a drive cycle to confirm the repair

Related codes

Nearby codes in this group

• P0538A/C Evaporator Temperature Sensor Circuit High
• P0540Intake Air Heater 'A' Circuit
• P0537A/C Evaporator Temperature Sensor Circuit Low
• P0541Intake Air Heater 'A' Circuit Low
• P0536A/C Evaporator Temperature Sensor Circuit Range/Performance
• P0542Intake Air Heater 'A' Circuit High
• P0535A/C Evaporator Temperature Sensor Circuit
• P0543Intake Air Heater 'A' Circuit Open