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P0844 Transmission Fluid Pressure Sensor/Switch "A" Circuit Intermittent

The OBD2 code P0844 indicates that there is an intermittent issue with the transmission fluid pressure sensor or switch "A," which may affect the transmission's ability to monitor fluid pressure accurately

Definition

The OBD2 code P0844 indicates that there is an intermittent issue with the transmission fluid pressure sensor or switch "A," which may affect the transmission's ability to monitor fluid pressure accurately

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 installed or damaged transmission components

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 Wiring and Connectors

    Visual Inspection: Check the wiring 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 transmission fluid pressure 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 service manual

  6. 6. Check Transmission Fluid Level and Condition

    Fluid Level: Ensure that the transmission fluid is at the correct level. Low fluid levels 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 replaced

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

    Connections: Check the TCM connections for any signs of damage or corrosion

  9. 9. Software Updates

    Ensure that the TCM has the latest software updates, as manufacturers sometimes release updates to fix known issues

  10. 10. Perform a Functional Test

    Road Test: Take the vehicle for a test drive to see if the code reappears. Pay attention to any unusual transmission behavior, such as slipping or harsh shifting

  11. 11. 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

  12. 12. Replace the Sensor (if necessary)

    If the sensor is found to be faulty after testing, replace it with a new one. Make sure to clear the codes and test drive the vehicle again to see if the issue is resolved

  13. 13. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P0844 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations for this issue

  14. 14. Seek Professional Help

    If the problem persists after performing these steps, it may be best to consult a professional mechanic or transmission specialist for further diagnosis. By following these steps, you should be able to identify the cause of the P0844 code and take appropriate action to resolve the issue