Gear 5 Incorrect Ratio
The Powertrain Control Module (PCM) or Transmission Control Module (TCM) detected that the actual gear ratio for 5th gear does not match the expected gear ratio. This is determined by comparing the transmission input (turbine) speed sensor signal with the output speed sensor signal while the transmission is commanded into 5th gear.
This code indicates a significant transmission issue that can lead to complete transmission failure if ignored. It is highly recommended to stop driving the vehicle to prevent further internal damage and avoid being stranded.
Common symptoms
- Check Engine Light is illuminated
- Transmission slips when shifting into or driving in 5th gear
- Vehicle fails to shift into 5th gear entirely
- Harsh or delayed shifting into 5th gear
- Decreased fuel economy and higher than normal engine RPMs at highway speeds
Likely causes
- Low or dirty transmission fluid
- Worn or damaged internal transmission friction clutches or bands for 5th gear
- Faulty shift solenoid responsible for 5th gear actuation
- Defective transmission valve body
- Faulty input or output speed sensors
- Internal hydraulic pressure loss or seal failure
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Fluid that is low, burnt, or heavily contaminated with metal shavings, indicating internal wear or a leak.
Scan for other related DTCs, especially speed sensor or solenoid codes.
Look for: Additional codes that might pinpoint an electrical or sensor failure rather than an internal mechanical failure.
Monitor input and output speed sensor data via a scan tool while driving.
Look for: Erratic readings or a mismatch between the commanded gear ratio and the actual calculated ratio during the 5th gear shift.
Perform a transmission line pressure test.
Look for: Pressures that fall below the manufacturer's specifications, indicating a failing pump, valve body issue, or internal hydraulic leak.
Test the 5th gear shift solenoid electrically.
Look for: Resistance values outside of factory specifications or failure of the solenoid to actuate when manually energized.
This page explains the generic P0735 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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