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P1728 Transmission Slip Error

The OBD2 code P1728 indicates a transmission slip error, which means the transmission is not properly engaging or maintaining the expected gear ratio, leading to a loss of power transfer between the engine and the wheels

Definition

The OBD2 code P1728 indicates a transmission slip error, which means the transmission is not properly engaging or maintaining the expected gear ratio, leading to a loss of power transfer between the engine and the wheels

Common causes

  • Low transmission fluid level
  • Worn or damaged transmission components
  • Faulty transmission control module (TCM)
  • Malfunctioning speed sensors
  • Electrical issues or wiring problems
  • Faulty torque converter
  • Incorrect transmission fluid type
  • Software issues or updates needed in the TCM

Common misdiagnoses

  • Faulty transmission control module (TCM)
  • Worn or damaged transmission components
  • Low transmission fluid level or quality
  • Faulty speed sensors
  • Electrical issues or wiring problems
  • Incorrectly calibrated transmission
  • Engine performance issues
  • Faulty throttle position sensor (TPS)

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 slipping

  3. 3. Inspect the fluid for contamination, burning smell, or dark color. If the fluid is dirty or burnt, it may need to be changed

  4. 4. Inspect for Leaks

  5. 5. Look for any signs of transmission fluid leaks under the vehicle. Leaks can lead to low fluid levels and slipping

  6. 6. Check for Other Codes

  7. 7. Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues

  8. 8. Inspect Electrical Connections

  9. 9. Check the wiring and connectors related to the transmission control module (TCM) and the transmission itself. Look for corrosion, damage, or loose connections

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

  11. 11. If the TCM is malfunctioning, it may not be able to properly control the transmission, leading to slipping. Testing or reprogramming the TCM may be necessary

  12. 12. Examine the Transmission

  13. 13. If the above steps do not resolve the issue, a more in-depth inspection of the transmission may be required. This could include checking for worn clutches, bands, or other internal components

  14. 14. Check for Software Updates

  15. 15. Sometimes, manufacturers release software updates for the TCM that can resolve issues related to transmission performance. Check with the dealership for any available updates

  16. 16. Perform a Road Test

  17. 17. Conduct a road test to replicate the conditions under which the code was triggered. Pay attention to how the transmission shifts and if any slipping occurs

  18. 18. Consult a Professional

  19. 19. If you are unable to diagnose or fix the issue, it may be best to consult a professional mechanic or transmission specialist who can perform a more thorough diagnosis

  20. 20. Consider Fluid Change or Flush

  21. 21. If the fluid is old or contaminated, consider performing a fluid change or flush, as this can sometimes resolve slipping issues. Remember that transmission issues can be complex, and while these steps can help identify the problem, some issues may require specialized tools and knowledge to diagnose and repair effectively