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Engine-Codes – Generic – P0729

P0729 Code - Automatic Transmission 6th Gear Incorrect Ratio

Quick Answer

When the diagnostic trouble code P0729 is triggered, it means that the automatic transmission is detecting an incorrect ratio in the 6th gear. Common causes include Faulty transmission speed sensor, Malfunctioning gear shift solenoid, Low transmission fluid levels. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0729 indicates Automatic Transmission 6th Gear Incorrect Ratio.
Common causes
Common causes include Faulty transmission speed sensor, Malfunctioning gear shift solenoid, Low transmission fluid levels.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0729 Description

When the diagnostic trouble code P0729 is triggered, it means that the automatic transmission is detecting an incorrect ratio in the 6th gear. This can lead to various performance issues in the vehicle, affecting its overall drivability. The transmission control module (TCM) monitors the gear ratios to ensure smooth shifting and optimal performance. When the TCM detects that the actual gear ratio does not match the expected ratio for 6th gear, it will trigger this code.

OBDII Code P0729 - Automatic Transmission 6th Gear Incorrect Ratio
P0729 Code - Automatic Transmission 6th Gear Incorrect Ratio

Common Causes of P0729

  1. Faulty transmission speed sensor
  2. Malfunctioning gear shift solenoid
  3. Low transmission fluid levels
  4. Internal transmission damage
  5. Electrical issues in the transmission control module

Symptoms of P0729

  1. Delayed or harsh shifting in 6th gear
  2. Slipping or jerking when accelerating in 6th gear
  3. Decreased fuel efficiency
  4. Illuminated check engine light
  5. Transmission overheating

How to Fix P0729

  1. Perform a diagnostic scan to retrieve the trouble code and identify the specific issue causing the incorrect gear ratio.
  2. Inspect the transmission speed sensor and gear shift solenoid for any signs of damage or malfunction.
  3. Check the transmission fluid level and quality, topping up or replacing as needed.
  4. Conduct a thorough inspection of the transmission components for any internal damage, such as worn gears or clutches.
  5. Reset the TCM and road test the vehicle to ensure the issue has been resolved.

Cost to Fix P0729

The typical repair costs for addressing the P0729 code can vary depending on the root cause of the issue. On average, you can expect to pay anywhere from $200 to $800 for parts and labor. However, it's essential to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It's advisable to consult with a professional technician to get a more accurate estimate based on your specific circumstances.

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Code P0729 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0729 Code

1. What are the common symptoms of OBDII code P0729 (Automatic Transmission 6th Gear Incorrect Ratio)?

- Common symptoms include erratic shifting behavior, transmission slipping, and a noticeable decrease in fuel efficiency.

2. What are the potential causes of OBDII code P0729?

- Possible causes include a faulty transmission speed sensor, issues with the transmission control module, low transmission fluid levels, or a damaged wiring harness.

3. How can I diagnose OBDII code P0729?

- Diagnosing this code typically involves using a scan tool to retrieve the specific trouble code, checking for any related codes, and performing a visual inspection of the transmission components.

4. Can driving with OBDII code P0729 cause further damage to the vehicle?

- Continuing to drive with this code may lead to more severe transmission issues over time, potentially causing long-term damage if left unresolved.

5. What are some repair tips for fixing OBDII code P0729?

- Repair tips may include checking and replacing the transmission speed sensor, inspecting the wiring for any damage, ensuring the transmission fluid is at the correct level and in good condition, and resetting the trouble code after repairs are made.

6. Is it safe to continue driving with OBDII code P0729 present?

- It is not recommended to drive with this code present, as it can lead to further transmission problems and potential safety hazards on the road.

7. How much does it typically cost to repair OBDII code P0729?

- The cost of repairs can vary depending on the specific cause of the code, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Can I reset OBDII code P0729 myself, or do I need a professional mechanic?

- You can attempt to reset the code yourself using an OBDII scanner, but it is important to address the underlying issue causing the code to prevent it from reoccurring.

9. Are there any preventive measures to avoid OBDII code P0729 in the future?

- Regular maintenance of the transmission system, such as checking and changing the transmission fluid according to the manufacturer's recommendations, can help prevent issues that may trigger this code.

10. Will OBDII code P0729 cause the vehicle to go into "limp mode"?

- In some cases, the vehicle's computer may activate "limp mode" to protect the transmission from further damage when detecting this code, limiting the vehicle's performance until the issue is resolved.

Discuss the causes and fixes for P0729 OBDII Code

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  • hi have p0729 p0735 replace with new transmission same problem. reprogram tcm same. trans shift ok but kick out of 6th an 5th gear.i look at out put speed sensor did not see an problem with transfer case tone ring . still looking tcm must see a wrong gear .ratio rpm

    Reply to Comment

  • good day I have a problem with the P0729 and P0735 which gear 6 and 5 are incorrect ratio, then I just check connectors and clear the codesI drove for almost 10 km luckily does'nt comeback the code again,But Im still worried can be worse when it come it again. anyone can suggest what I need replace? my car 2010 ford falcon xt 6 speed auto

    Reply to Comment