Hydraulic Oil Temperature Sensor Circuit
Diagnostic trouble code P0937 indicates that the transmission control module has detected an abnormal electrical signal from the hydraulic oil temperature sensor circuit. The module sets this code when the voltage or resistance from the sensor falls outside the expected operating range, preventing accurate fluid temperature monitoring.
While the vehicle can usually still be driven, prolonged driving with this code can lead to poor shift quality and potential transmission damage from unmonitored overheating. It should be diagnosed and repaired soon to ensure transmission longevity.
Common symptoms
- Illuminated Check Engine Light
- Harsh or erratic transmission shifting
- Delayed gear engagement
- Transmission entering limp-home mode
- Transmission overheating warning (if equipped)
Likely causes
- Faulty hydraulic oil temperature sensor
- Corroded, damaged, or loose wiring and connectors in the sensor circuit
- Low or heavily contaminated transmission fluid
- Internal transmission wiring harness failure
- Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Fluid that is significantly low, burnt, or heavily contaminated with debris, which can affect sensor operation and overall transmission health.
Visually inspect the wiring and connectors associated with the hydraulic oil temperature sensor.
Look for: Frayed wires, melted insulation, pushed-out pins, or corrosion inside the connector that could cause high resistance or an open circuit.
Use a scan tool to monitor the live data for the hydraulic oil temperature.
Look for: A temperature reading that is stuck at an extreme value (like -40 degrees or 300+ degrees) or fluctuates erratically, indicating a circuit or sensor failure.
Measure the resistance of the hydraulic oil temperature sensor using a digital multimeter.
Look for: Resistance values that do not match the manufacturer's specified range for the current ambient or operating temperature, indicating a failed internal sensor thermistor.
Test the reference voltage and ground circuits at the sensor connector.
Look for: A missing 5-volt reference signal or a poor ground connection, which points to a wiring issue between the sensor and the control module.
This page explains the generic P0937 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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