A/C Evaporator Temperature Sensor Circuit Low
The P0537 code indicates that the A/C evaporator temperature sensor circuit is reading a voltage lower than the expected range. This sensor monitors the temperature of the evaporator core to prevent freezing and control A/C operation. A low circuit signal can be caused by a faulty sensor, wiring issues (short to ground), or a problem with the PCM. This can lead to improper A/C system function, such as the compressor not engaging or the system cycling incorrectly.
01. Most Common Causes
- Faulty A/C evaporator temperature sensor
- Short to ground in sensor wiring or connector
- Corroded or damaged sensor connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- A/C system not blowing cold air
- A/C compressor not engaging
- Erratic A/C operation or rapid cycling
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0537 and check for other related codes.
Step 2: Visually inspect the A/C evaporator temperature sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Disconnect the sensor and measure its resistance with a multimeter; compare to manufacturer specifications (typically 2-10 kΩ at 77°F).
Step 4: Check for a short to ground by measuring resistance between sensor signal wire and ground; should be infinite (open).
Step 5: If sensor and wiring are okay, test the PCM's ability to read the sensor by backprobing the signal wire and monitoring voltage with scan tool.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the A/C system may not work properly. The vehicle's engine and drivetrain are not affected.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, including parts (sensor $20-$50) and labor (0.5-1 hour).