P0729 2015 GMC Sierra Code - Transmission 6th Gear Ratio Incorrect
Quick Answer
The transmission turbine speed sensor and vehicle speed sensor are hall-effect sensors. Common causes include Low transmission fluid level, Shift solenoid mechanical fault, Faulty Turbine Sensor. 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 2015 GMC Sierra indicates Transmission 6th Gear Ratio Incorrect.
- Common causes
- Common causes include Low transmission fluid level, Shift solenoid mechanical fault, Faulty Turbine Sensor.
- 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.
Code P0729 2015 GMC Sierra Description
The TCM provides a 9 V reference circuit and a signal circuit to each of the sensors. As the 1-2-3-4-5-6 clutch piston housing and transmission output shaft or transfer case output rotates, the sensors produce a signal frequency based on the teeth on the reluctor wheel. The TCM calculates the transmission gear ratio based on the speed sensor signals and compares the calculated gear ratio to the commanded gear ratio.
The Diagnostic Trouble Code (DTC) will be set when the TCM detects the calculated gear ratio with 6th gear commanded differs from the known 6th gear ratio for 2 s.
What are the Possible Causes of the DTC P0729 2015 GMC Sierra?
- Low transmission fluid level
- Shift solenoid mechanical fault
- Faulty Turbine Sensor
- Faulty Output Speed Sensor
How to Fix the DTC P0729 2015 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0729 2015 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0729 2015 GMC Sierra Code
1. What does the OBDII code P0729 mean for a 2015 GMC Sierra?
P0729 indicates that the transmission’s 6th gear ratio is incorrect, meaning the vehicle's computer has detected a mismatch between the expected and actual gear ratio.
2. What are the common symptoms of code P0729 in a 2015 GMC Sierra?
Symptoms may include slipping in 6th gear, poor fuel efficiency, difficulty shifting, transmission overheating, or the check engine light turning on.
3. What causes the P0729 code in a 2015 GMC Sierra?
Common causes include faulty transmission solenoids, low or dirty transmission fluid, worn clutch packs, damaged gears, or issues with the transmission control module.
4. Can I drive my 2015 GMC Sierra with the P0729 code?
Driving with this code may lead to further transmission damage or unsafe driving conditions. It’s best to address the issue promptly.
5. How do I diagnose the P0729 code in a 2015 GMC Sierra?
Diagnosis involves checking the transmission fluid condition and level, inspecting the solenoids and wiring, and using a scan tool to monitor live transmission data.
6. How do I fix the P0729 code on a 2015 GMC Sierra?
Repairs may include replacing damaged solenoids, flushing and refilling transmission fluid, repairing worn clutch packs, or reprogramming or replacing the transmission control module.
7. Can dirty transmission fluid cause the P0729 code?
Yes, dirty or low transmission fluid can cause incorrect gear ratios by affecting hydraulic pressure and the operation of solenoids.
8. How much does it cost to repair the P0729 code on a 2015 GMC Sierra?
Repair costs vary depending on the exact issue, ranging from $150 for fluid replacement to over $3,000 for major transmission repairs.
9. Will resetting the check engine light fix the P0729 code on a 2015 GMC Sierra?
Resetting the light may temporarily clear the code, but the underlying issue must be addressed to prevent the code from returning.
10. Can a faulty transmission control module cause the P0729 code?
Yes, a malfunctioning transmission control module can send incorrect signals, leading to gear ratio errors like P0729.
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