P0874 Transmission Fluid Pressure Sensor/Switch "C" Circuit Intermittent

Definition

Common causes

• Faulty transmission fluid pressure sensor
• Wiring issues (damaged, frayed, or corroded wires)
• Poor electrical connections
• Faulty transmission control module (TCM)
• Low transmission fluid level
• Contaminated transmission fluid
• Internal transmission problems
• Faulty transmission fluid pressure switch

Common misdiagnoses

• Faulty transmission fluid pressure sensor
• Wiring issues or short circuits in the sensor circuit
• Transmission control module (TCM) failure
• Low transmission fluid level or contamination
• Faulty transmission solenoids
• Internal transmission problems
• Engine control module (ECM) issues
• Incorrectly diagnosed electrical issues elsewhere in the vehicle

Troubleshooting steps

1. 1. Check for Additional Codes

   Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are other issues affecting the transmission

2. 2. Inspect the Wiring and Connectors

   Visual Inspection: Check the wiring harness and connectors associated with the Transmission Fluid Pressure Sensor. Look for signs of damage, corrosion, or loose connections

3. 3. Connector Condition

   Ensure that the connectors are clean and securely attached. Corrosion or dirt can cause intermittent connections

4. 4. Test the Transmission Fluid Pressure Sensor

   Resistance Check: Use a multimeter to measure the resistance of the sensor. Compare the readings to the specifications provided in the vehicle’s service manual

5. 5. Voltage Check

   With the ignition on (engine off), check the voltage at the sensor connector. Ensure it matches the expected voltage as per the manufacturer’s specifications

6. 6. Check Transmission Fluid Level and Condition

   Fluid Level: Ensure that the transmission fluid is at the correct level. Low fluid can cause erratic sensor readings

7. 7. Fluid Condition

   Inspect the fluid for contamination or burning. If the fluid is dirty or smells burnt, it may need to be changed

8. 8. Inspect the Transmission Control Module (TCM)

   Check for any signs of damage or corrosion on the TCM. Ensure that it is properly connected and functioning

9. 9. Perform a Wiggle Test

   With the vehicle running, gently wiggle the wiring harness and connectors related to the transmission fluid pressure sensor. If the code returns or the transmission behavior changes, it may indicate a wiring issue

10. 10. Check for Ground Issues

    Ensure that the ground connections for the transmission and the sensor are secure and free of corrosion. Poor grounding can lead to intermittent issues

11. 11. Scan for Freeze Frame Data

    Review the freeze frame data associated with the P0874 code. This data can provide insight into the conditions under which the code was triggered

12. 12. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the codes and take the vehicle for a test drive to see if the code returns

13. 13. Replace the Sensor (if necessary)

    If all other checks are satisfactory and the issue persists, consider replacing the Transmission Fluid Pressure Sensor. 1

14. 14. Consult a Professional

    If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic or technician who has experience with transmission issues.Conclusion By following these troubleshooting steps, you can systematically identify and address the cause of the P0874 code. Always refer to the specific service manual for your vehicle for detailed specifications and procedures