B1390 – Oil Temperature Sensor Circuit Short To Ground

The ODBII code B1390 indicates a malfunction in the oil temperature sensor circuit, specifically that there is a short to ground, which means the circuit is unintentionally connected to the ground, causing incorrect readings or failure of the sensor.

The severity of ODBII code B1390 is moderate.

Common Causes For: B1389 Oil Temperature Sensor Circuit Failure

• Damaged wiring or connectors
• Shorted sensor
• Faulty oil temperature sensor
• Corroded connections
• Grounding issues in the circuit
• Faulty engine control module (ECM)

Common misdiagnosis for B1390 Oil Temperature Sensor Circuit Short To Ground

• Faulty oil temperature sensor
• Wiring issues or damaged harness
• Engine control module (ECM) malfunction
• Shorted or corroded connectors
• Incorrect oil level or type
• Other sensor failures (e.g., coolant temperature sensor)
• Faulty gauge or display issues
• Grounding issues in the electrical system

Common Troubleshooting Steps

When dealing with an OBD-II code B1390, which indicates an “Oil Temperature Sensor Circuit Short to Ground,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check the Code and Freeze Frame Data: Use an OBD-II scanner to confirm the B1390 code is present.
• Review freeze frame data to understand the conditions under which the code was set.
• Visual Inspection: Inspect the wiring and connectors associated with the oil temperature sensor.
• Look for signs of damage, corrosion, or loose connections.
• Check for any frayed wires or shorts to ground in the harness.
• Test the Oil Temperature Sensor: Disconnect the oil temperature sensor and measure its resistance with a multimeter.
• Compare the resistance readings to the manufacturer’s specifications. If the sensor is out of spec, it may need to be replaced.
• Check for Short to Ground: With the sensor disconnected, use a multimeter to check for continuity between the sensor signal wire and ground.
• If there is continuity, there is likely a short in the wiring harness that needs to be repaired.
• Inspect the Ground Circuit: Check the ground connections for the oil temperature sensor and ensure they are clean and secure.
• Test the ground circuit for continuity and proper voltage.
• Check the Power Supply: Verify that the oil temperature sensor is receiving the correct voltage from the vehicle’s power supply.
• If the voltage is incorrect, trace back to the power source to identify any issues.
• Scan for Additional Codes: Check for any other related trouble codes that may provide additional context or indicate a broader issue.
• Clear the Codes and Test Drive: After performing repairs or adjustments, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code reappears.
• Consult Service Manual: If the issue persists, consult the vehicle’s service manual for specific diagnostic procedures related to the oil temperature sensor circuit.
• Seek Professional Help: If you are unable to resolve the issue after these steps, consider seeking assistance from a professional mechanic or automotive technician.Additional Tips: – Always ensure that you are working safely and disconnect the battery when working on electrical components. – Document any changes or repairs made during the troubleshooting process for future reference. By following these steps, you should be able to identify and address the cause of the B1390 code effectively.