WOMS
P code powertrain High severity

P0735 Gear 5 Incorrect ratio

The OBD2 code P0735 indicates that the transmission control module has detected an incorrect gear ratio in the fifth gear, suggesting a problem with the transmission's ability to shift into or maintain that gear

Definition

The OBD2 code P0735 indicates that the transmission control module has detected an incorrect gear ratio in the fifth gear, suggesting a problem with the transmission's ability to shift into or maintain that gear

Common causes

  • Faulty transmission control module (TCM)
  • Worn or damaged transmission components
  • Low transmission fluid level
  • Contaminated transmission fluid
  • Faulty input or output speed sensors
  • Malfunctioning solenoids
  • Electrical issues (wiring or connectors)
  • Incorrectly installed or damaged transmission filter
  • Software issues in the TCM
  • Mechanical failure within the transmission

Common misdiagnoses

  • Transmission fluid issues
  • Faulty transmission control module (TCM)
  • Worn or damaged transmission components
  • Incorrectly installed or malfunctioning shift solenoids
  • Electrical wiring problems
  • Faulty vehicle speed sensor (VSS)
  • Engine control module (ECM) issues
  • Clutch problems (in manual transmissions)
  • Incorrect gear ratio due to tire size changes
  • Software issues or outdated firmware in the TCM

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 changing it

  4. 4. Inspect for Leaks

  5. 5. Look for any signs of transmission fluid leaks. Leaks can lead to low fluid levels and affect transmission performance

  6. 6. Scan for Additional Codes

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

  8. 8. Check Electrical Connections

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

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

  11. 11. If the TCM is malfunctioning, it may not be sending the correct signals to the transmission. Testing or reprogramming the TCM may be necessary

  12. 12. Inspect the Transmission Solenoids

  13. 13. The solenoids control the flow of transmission fluid. A faulty solenoid can lead to incorrect gear ratios. Test the solenoids for proper operation

  14. 14. Check for Mechanical Issues

  15. 15. Inspect the transmission for internal mechanical problems, such as worn gears, clutches, or bands. A transmission rebuild or replacement may be necessary if significant wear is found

  16. 16. Perform a Transmission Fluid Flush

  17. 17. If the fluid is contaminated, a flush may help improve performance. However, this should be done with caution, as it can sometimes exacerbate existing issues

  18. 18. Road Test the Vehicle

  19. 19. After performing the above checks, take the vehicle for a test drive to see if the issue persists. Pay attention to how the transmission shifts through all gears

  20. 20. Consult a Professional

  21. 21. If the problem remains unresolved after these steps, it may be best to consult a professional mechanic or transmission specialist for further diagnosis and repair. Always remember to follow safety precautions when working on vehicles, and if you're unsure about any step, it's best to seek professional assistance