P0537 - A/C Evaporator Temperature Sensor Circuit Low
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0537 is set when the Engine Control Module (ECM) or Climate Control Module (CCM) detects a voltage signal from the A/C evaporator temperature sensor that is below the calibrated limit (typically near 0V). This indicates a short to ground in the signal circuit. The sensor is an NTC resistor (Negative Temperature Coefficient). The control module uses this data to cycle the A/C compressor and prevent the evaporator fins from icing up, which would restrict airflow.
Possible Causes
Short to ground in the A/C evaporator temperature sensor wiring.
Faulty evaporator temperature sensor (internal short).
Corroded or damaged connector at the sensor.
Faulty Climate Control Module (CCM) or ECM.
Symptoms
Recommended Solution
- STEP 1: Perform a visual inspection of the wiring and connectors under the dashboard near the evaporator case. Look for frayed or pinched wires.
- STEP 2: Disconnect the sensor and measure resistance using a multimeter. At 68°F (20°C), it should typically read 2k-5k Ohms. If it reads near 0 Ohms, the sensor is internally shorted.
- STEP 3: Check reference voltage (usually 5V) at the connector with ignition on. Test the signal wire for continuity to ground to confirm a short circuit.
- STEP 4: If wiring and reference voltages are within spec, replace the evaporator temperature sensor.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P0537 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.