WOMS
P code powertrain High severity

P1731 1-2 Shift Malfunction

The OBD2 code P1731 indicates a malfunction in the 1-2 shift of the transmission, typically related to issues with the transmission control system or components affecting the shifting process

Definition

The OBD2 code P1731 indicates a malfunction in the 1-2 shift of the transmission, typically related to issues with the transmission control system or components affecting the shifting process

Common causes

  • Faulty transmission control module (TCM)
  • Malfunctioning shift solenoid
  • Low transmission fluid level
  • Contaminated or degraded transmission fluid
  • Worn or damaged transmission components
  • Electrical issues (wiring or connectors)
  • Faulty throttle position sensor (TPS)
  • Incorrectly adjusted transmission linkage
  • Engine control module (ECM) issues
  • Mechanical failure within the transmission

Common misdiagnoses

  • Transmission fluid issues (low or dirty fluid)
  • Faulty transmission control module (TCM)
  • Wiring or connector problems
  • Faulty speed sensors
  • Incorrectly diagnosed mechanical transmission issues
  • Engine performance issues (e.g., misfires)
  • Throttle position sensor (TPS) problems
  • Incorrectly calibrated or faulty shift solenoids

Troubleshooting steps

  1. 1. Check Transmission Fluid Level and Condition

  2. 2. Ensure that the transmission fluid is at the correct level. Low fluid can cause shifting issues

  3. 3. Inspect the fluid for contamination, burning smell, or dark color. If the fluid is dirty or burnt, consider a transmission fluid change

  4. 4. Inspect for Leaks

  5. 5. Look for any signs of transmission fluid leaks around the transmission pan, seals, and hoses. Address any leaks found

  6. 6. Scan for Additional Codes

  7. 7. Use an OBD-II scanner to check for any other related trouble codes that may provide more context to the issue

  8. 8. Check Transmission Wiring and Connectors

  9. 9. Inspect the wiring harness and connectors related to the transmission for any signs of damage, corrosion, or loose connections

  10. 10. Test the Transmission Control Module (TCM)

  11. 11. The TCM may be malfunctioning. Check for proper operation and any software updates that may be needed

  12. 12. Inspect the Shift Solenoids

  13. 13. The shift solenoids control the flow of transmission fluid for shifting. Test the solenoids for proper operation and replace any that are faulty

  14. 14. Examine the Throttle Position Sensor (TPS)

  15. 15. A malfunctioning TPS can affect shifting. Test the TPS for proper voltage and operation

  16. 16. Check for Mechanical Issues

  17. 17. Inspect the transmission for any internal mechanical issues, such as worn clutches or bands, which may require a more in-depth inspection or rebuild

  18. 18. Perform a Road Test

  19. 19. Conduct a road test to observe the shifting behavior. Pay attention to any unusual noises or symptoms during the shift from 1st to 2nd gear

  20. 20. Consult Technical Service Bulletins (TSBs)

  21. 21. Check for any TSBs related to the specific make and model of the vehicle, as there may be known issues or fixes for the P1731 code. 1

  22. 22. Professional Diagnosis

  23. 23. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or transmission specialist for a more thorough diagnosis. Always remember to follow safety precautions when working on a vehicle and consult the vehicle's service manual for specific procedures and specifications