P0731 GMC Code - Transmission 1st 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
- P0731 GMC indicates Transmission 1st 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 P0731 GMC 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 1st gear commanded differs from the known 1st gear ratio for 2 s.
What are the Possible Causes of the DTC P0731 GMC?
- Low transmission fluid level
- Shift solenoid mechanical fault
- Faulty Turbine Sensor
- Faulty Output Speed Sensor
How to Fix the DTC P0731 GMC?
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 P0731 GMC 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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Information for Specific GMC Models
- P0731 2014 GMC Sierra — Transmission 1st Gear Ratio Incorrect
- P0731 2015 GMC Sierra — Transmission 1st Gear Ratio Incorrect
- P0731 2016 GMC Sierra — Transmission 1st Gear Ratio Incorrect
- P0731 2017 GMC Sierra — Transmission 1st Gear Ratio Incorrect
- P0731 2018 GMC Sierra — Transmission 1st Gear Ratio Incorrect
Frequently Asked Questions about P0731 GMC Code
1. What does the OBDII code P0731 mean on a GMC vehicle?
P0731 indicates that the transmission control module has detected an incorrect gear ratio in 1st gear.
2. What are the common symptoms of code P0731 in a GMC?
Symptoms include transmission slipping, harsh shifting, poor acceleration, decreased fuel efficiency, and the check engine light turning on.
3. What causes the P0731 code to appear in a GMC?
Common causes include low or dirty transmission fluid, a faulty transmission solenoid, damaged internal transmission components, or issues with the transmission control module.
4. Can driving with a P0731 code damage my GMC?
Yes, continuing to drive with this code can cause further damage to the transmission and lead to more costly repairs.
5. How can I fix the P0731 code on my GMC?
Start by checking the transmission fluid level and condition, then inspect the transmission solenoids, wiring, and connectors. If necessary, consult a professional to diagnose and repair internal transmission issues.
6. Is low transmission fluid a common cause of P0731 on a GMC?
Yes, low or dirty transmission fluid is one of the most common causes of the P0731 code and should be checked first.
7. How much does it cost to repair a P0731 code on a GMC?
The repair cost varies based on the issue. Fluid replacement may cost under $100, while internal transmission repairs or replacements could exceed $1,000.
8. Can a faulty transmission solenoid trigger the P0731 code in a GMC?
Yes, a malfunctioning solenoid can disrupt proper gear engagement and lead to the P0731 code.
9. Will resetting the check engine light fix the P0731 code on my GMC?
Resetting the light may clear the code temporarily, but the underlying issue must be resolved to prevent the code from returning.
10. Do I need a mechanic to fix the P0731 code on my GMC?
While some issues like fluid checks can be done at home, diagnosing and repairing transmission problems often require professional expertise and specialized tools.
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