The P0735 trouble code is a diagnostic trouble code (DTC) that signifies an issue with the automatic transmission’s ability to shift into fifth gear. Specifically, it indicates a “Gear 5 Incorrect Ratio,” meaning that the transmission control module (TCM) has detected a discrepancy between the expected and actual gear ratios during operation. This code is critical as it can lead to poor vehicle performance, reduced fuel efficiency, and potential long-term damage to the transmission system if not addressed promptly.
| P0735 Code Meaning | P0735 Code Common Causes |
|---|---|
| Gear 5 Incorrect Ratio | Internal transmission failure |
| Transmission not engaging fifth gear correctly | Malfunctioning TCM or PCM |
| Improper input/output speed sensor readings | Faulty shift solenoid |
| Transmission fluid issues (low or contaminated) | Wiring or connector problems |
| Mechanical transmission problems | Faulty valve body |
Symptoms of P0735 Code
Understanding the symptoms associated with the P0735 code is crucial for early diagnosis and prevention of further damage. Common symptoms include:
- Check Engine Light: The most immediate indication that something is wrong.
- Poor Fuel Economy: Increased fuel consumption due to inefficient shifting.
- Delayed Shifting: Noticeable lag when shifting from lower gears to fifth.
- Transmission Slipping: The vehicle may unexpectedly lose power or fail to engage properly in fifth gear.
- Unusual Noises: Grinding or whining sounds from the transmission, especially during shifting.
Technical Explanation of P0735 Code
The P0735 code is triggered when there is a mismatch between the expected and actual rotational speeds of the input and output speed sensors in the transmission. The TCM monitors these sensors to determine if the vehicle is in the correct gear. If the TCM detects that the input speed does not correlate with what it expects for fifth gear, it sets the P0735 code.
Key Components Involved
- Transmission Control Module (TCM): The brain of the transmission system, responsible for managing gear shifts based on sensor inputs.
- Input Speed Sensor: Measures the rotational speed of the input shaft.
- Output Speed Sensor: Measures the speed of the output shaft.
- Shift Solenoids: Control fluid flow within the transmission to engage different gears.
Step-by-Step Diagnosis of P0735 Code
Diagnosing a P0735 code requires a systematic approach to identify and rectify the underlying issue. Here’s how you can perform a step-by-step diagnosis:
- Scan for Codes:
- Use an OBD-II scanner to retrieve all stored codes. Note any additional codes that may provide context for the P0735.
- Visual Inspection:
- Inspect wiring and connectors related to the TCM, input/output speed sensors, and shift solenoids for damage or corrosion.
- Check Transmission Fluid:
- Verify fluid level and condition. Low or dirty fluid can lead to shifting issues. Replace if necessary.
- Test Drive:
- Conduct a test drive under various conditions while monitoring how the transmission behaves, particularly when attempting to shift into fifth gear.
- Sensor Testing:
- Use a multimeter to test input and output speed sensors for proper voltage and resistance readings.
- Shift Solenoid Check:
- Test shift solenoids for functionality; faulty solenoids can prevent proper gear engagement.
- Inspect Internal Components:
- If all else fails, internal transmission components may need inspection for wear or failure.
Solution Methods for P0735 Code
Once you’ve diagnosed the issue causing the P0735 code, it’s time to implement solutions. Here are common methods:
- Fluid Change: If low or contaminated fluid is identified, replace it with manufacturer-recommended fluid.
- Repair Wiring Issues: Fix any damaged wiring or connectors related to transmission control and sensors.
- Replace Faulty Sensors: If tests indicate malfunctioning input/output speed sensors, replace them.
- Shift Solenoid Replacement: If solenoids are found defective, they should be replaced to restore proper shifting function.
- Internal Repairs: For severe cases involving internal transmission failure, consider rebuilding or replacing the transmission as necessary.
Cost Estimates
Cost estimates for repairs related to the P0735 code can vary significantly based on location, labor rates, and vehicle make/model:
- Transmission Fluid Change: $100 – $200
- Sensor Replacement (Input/Output): $150 – $300 each
- Shift Solenoid Replacement: $200 – $400
- Transmission Repair/Rebuild: $1,500 – $4,000+
Warnings and Recommendations
Always consult a certified mechanic if you are unsure about diagnosing or repairing your vehicle’s transmission issues. Attempting complex repairs without proper knowledge can lead to further damage and increased repair costs.
Additionally, ignoring symptoms associated with the P0735 code can lead to more severe transmission problems over time, potentially resulting in complete transmission failure.
Closing Paragraph
In conclusion, understanding and addressing the P0735 trouble code is essential for maintaining your vehicle’s performance and longevity. By recognizing symptoms early and following a systematic diagnostic approach, vehicle owners and DIY mechanics can effectively troubleshoot this issue. Whether it’s a simple fluid change or a more complex internal repair, addressing this code promptly will help ensure your vehicle operates smoothly and efficiently.
Frequently Asked Questions About P0735
- What does P0735 mean?
P0735 indicates “Gear 5 Incorrect Ratio,” meaning there is an issue with shifting into fifth gear. - What are common causes of P0735?
Common causes include low or dirty transmission fluid, faulty sensors, internal mechanical failures, and issues with shift solenoids. - How serious is a P0735 code?
A P0735 code should be addressed promptly as it can lead to poor performance and potential damage to your transmission. - Can I drive my car with a P0735 code?
While it may be possible to drive short distances, it is not recommended due to potential further damage. - How do I fix a P0735 code?
Fixing a P0735 code typically involves checking fluid levels, inspecting sensors/solenoids, and possibly repairing or replacing internal components. - Is professional help needed for P0735?
If you are not experienced in automotive repairs, it is advisable to seek professional help for accurate diagnosis and repair. - What tools do I need to diagnose P0735?
An OBD-II scanner is essential for reading trouble codes; additional tools may include a multimeter for testing sensors. - Can other codes appear with P0735?
Yes, other related codes may appear such as P0730 through P0736 indicating similar issues with different gears.