B1391 – Oil Level Switch Circuit Failure

The ODBII code B1391 indicates a malfunction in the oil level switch circuit, which may involve issues with the switch itself, wiring, or connectors related to monitoring the engine oil level.

The severity of ODBII code B1391 is generally considered moderate.

Common Causes For: B1390 Oil Temperature Sensor Circuit Short To Ground

• Faulty oil level switch
• Damaged wiring or connectors
• Short circuit in the oil level switch circuit
• Open circuit in the oil level switch circuit
• Corrosion at the connector terminals
• Faulty engine control module (ECM) or powertrain control module (PCM)

Common misdiagnosis for B1391 Oil Level Switch Circuit Failure

• Faulty oil level sensor
• Wiring issues or shorts in the circuit
• Faulty engine control module (ECM)
• Incorrect oil level readings due to oil contamination
• Problems with the oil pressure sensor
• Issues with the vehicle’s electrical system or grounds
• Faulty connectors or terminals related to the oil level switch

Common Troubleshooting Steps

When dealing with OBD-II code B1391, which indicates an “Oil Level Switch Circuit Failure,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information regarding the oil level switch and its circuit. This can provide insights into the expected resistance values and wiring diagrams.
• Visual Inspection: **Wiring and Connectors: Inspect the wiring harness and connectors associated with the oil level switch for any signs of damage, corrosion, or loose connections.
• **Oil Level Switch: Check the oil level switch itself for any physical damage or signs of wear.
• Check Oil Level: Ensure that the engine oil level is within the recommended range. Low oil levels can sometimes trigger this code.
• Test the Oil Level Switch: **Resistance Test: Use a multimeter to measure the resistance of the oil level switch. Compare the readings to the specifications in the service manual.
• **Continuity Test: Check for continuity in the wiring leading to the oil level switch. This will help identify any breaks in the circuit.
• Inspect the Engine Control Module (ECM): Ensure that the ECM is functioning properly. Sometimes, a faulty ECM can cause erroneous codes. Check for any software updates or recalls related to the ECM.
• Check for Other Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide additional context for the issue.
• Clear the Code: After performing the above checks and repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Professional Diagnosis: If the issue persists after performing the above steps, consider seeking help from a professional mechanic. They may have specialized tools and knowledge to diagnose more complex issues.Additional Tips: – Always ensure that you are working in a safe environment and take necessary precautions when working on a vehicle. – If you are not comfortable performing these steps, it is advisable to consult with a professional technician. By following these troubleshooting steps, you should be able to identify and potentially resolve the issue related to the B1391 code.