Understand and Fix P0735: Gear 4 Incorrect Ratio

The transmission system in your car is responsible for smoothly shifting gears and delivering power to the wheels.

However, sometimes you may encounter issues with the transmission, such as error codes. One of the common error codes is P0735: Gear 4 Incorrect Ratio. In this article, we will explore what this error code means, its possible causes, and how to diagnose and fix it. So, let’s dive in and understand this issue better.

1. Introduction

The P0735 error code indicates that there is an incorrect ratio detected in the fourth gear of the transmission.

It typically occurs when the actual gear ratio deviates from the expected or programmed ratio. This error code is commonly seen in vehicles with automatic transmissions.

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2. Understanding the P0735 Error Code

What is the P0735 Error Code?

The P0735 error code specifically refers to an incorrect gear ratio detected in the fourth gear. Each gear in the transmission has a specific ratio that determines the speed and torque applied to the wheels. When the transmission control module (TCM) detects a significant difference between the expected and actual gear ratio, it triggers the P0735 error code.

Causes of the P0735 Error Code

There are several potential causes for the P0735 error code:

  1. Faulty Transmission Speed Sensor: The speed sensors in the transmission monitor the rotational speed of various components. If the speed sensor related to the fourth gear is malfunctioning, it can lead to an incorrect gear ratio error.
  2. Transmission Wiring Issues: Damaged or loose wiring connections between the TCM and the transmission can disrupt the transmission signals and cause incorrect gear ratio readings.

3. Diagnosing the P0735 Error Code

To effectively diagnose the P0735 error code, you can follow these steps:

Checking the Transmission Fluid

Start by checking the transmission fluid level and condition. Insufficient or contaminated transmission fluid can affect the gear shifting and lead to error codes. Consult your vehicle’s manual for the proper procedure to check the transmission fluid level and add more if necessary.

Inspecting the Transmission Wiring and Connectors

Next, carefully inspect the wiring harness and connectors related to the transmission. Look for any signs of damage, corrosion, or loose connections. If you notice any issues, repair or replace the affected wiring.

Testing the Transmission Speed Sensor

The transmission speed sensor provides crucial data to the TCM for determining the gear ratios. Using a multimeter, you can test the resistance or voltage output of the speed sensor. Compare the readings with the manufacturer’s specifications to determine if the sensor is functioning correctly. If it’s faulty, consider replacing it.

4. Fixing the P0735 Error Code

Once you have diagnosed the cause of the P0735 error code, you can proceed with the appropriate fix:

Replacing the Transmission Speed Sensor

If the speed sensor is found to be faulty, it’s recommended to replace it. Consult your vehicle’s repair manual or seek professional help to locate the speed sensor and follow the proper steps for replacement.

Repairing or Replacing the Transmission Wiring

In case the issue lies with the transmission wiring, you may need to repair or replace the damaged wiring. Ensure that the new wiring is properly connected and secured.

Flushing and Refilling the Transmission Fluid

If the error persists even after addressing the sensor or wiring issues, consider flushing and refilling the transmission fluid. Over time, the fluid can become contaminated or degraded, affecting the performance of the transmission. Consult your vehicle’s manual or seek professional assistance to perform a proper transmission fluid flush.

5. Tips for Preventing P0735 Error Code

To prevent the occurrence of the P0735 error code, consider the following tips:

  • Regular Maintenance: Stick to your vehicle’s recommended maintenance schedule, including regular transmission fluid changes and inspections.
  • Safe Driving Practices: Avoid aggressive driving and sudden gear changes, as they can put unnecessary stress on the transmission.
  • Address Issues Promptly: If you notice any unusual symptoms or warning lights related to the transmission, have them checked by a qualified mechanic to prevent potential issues.

6. Conclusion

Dealing with the P0735 error code can be frustrating, but by understanding its causes and following the correct diagnostic and repair steps, you can address the issue effectively. Remember to check the transmission fluid, inspect the wiring, and test the speed sensor. If needed, replace the faulty components and perform regular maintenance to prevent future problems.

7. FAQs

Q1. Can I continue driving my car with the P0735 error code?

While it may be possible to drive your car with the P0735 error code, it’s not recommended. Driving with an incorrect gear ratio can lead to further damage to the transmission. It’s best to address the issue promptly.

Q2. Can I fix the P0735 error code myself?

Depending on your level of experience and access to proper tools, you may be able to fix the P0735 error code yourself. However, it’s crucial to follow the correct diagnostic procedures and exercise caution while working on the transmission system.

Q3. How much does it cost to repair the P0735 error code?

The cost of repairing the P0735 error code can vary depending on the specific cause and the labor rates in your area. It’s recommended to consult with a qualified mechanic or repair shop to get an accurate estimate for your vehicle.

Remember, if you’re unsure or uncomfortable performing the repairs yourself, it’s always wise to seek professional assistance to ensure the job is done correctly and safely.