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Engine-Codes – GMC – P0742 GMC

P0742 GMC Code - Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance

Quick Answer

The P0742 code for GMC vehicles indicates a problem with the Torque Converter Clutch (TCC) system, specifically that it is stuck on or there is an issue with transmission hydraulic or mechanical performance. Common causes include Faulty TCC solenoid, Damaged wiring or connectors in the TCC circuit, 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
P0742 GMC indicates Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance.
Common causes
Common causes include Faulty TCC solenoid, Damaged wiring or connectors in the TCC circuit, 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 Aug 18, 2024
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Code P0742 GMC Description

The P0742 code for GMC vehicles indicates a problem with the Torque Converter Clutch (TCC) system, specifically that it is stuck on or there is an issue with transmission hydraulic or mechanical performance. The TCC is responsible for locking the torque converter to improve fuel efficiency and prevent slippage. When this system gets stuck on or malfunctions, it can lead to various performance issues with the vehicle's transmission.

OBDII Code P0742 GMC - Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance
P0742 GMC Code - Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance

Common Causes of P0742 GMC

  1. Faulty TCC solenoid.
  2. Damaged wiring or connectors in the TCC circuit.
  3. Low transmission fluid levels.
  4. Malfunctioning torque converter.
  5. Internal transmission issues.

Symptoms of P0742 GMC

  1. Harsh shifting or delayed engagement when changing gears.
  2. Decreased fuel efficiency.
  3. Engine stalling at idle.
  4. Overheating transmission fluid.
  5. Increased transmission slippage.

How to Fix P0742 GMC

  1. Perform a thorough diagnostic scan to confirm the P0742 code and identify the specific cause of the issue.
  2. Inspect and test the TCC solenoid and related wiring for faults or damage.
  3. Check transmission fluid levels and quality, and top up or replace if necessary.
  4. Inspect the torque converter for any signs of damage or malfunction.
  5. Address any internal transmission issues identified during diagnosis, such as worn clutches or gears.

Cost to Fix P0742 GMC

The cost of repairing a P0742 code can vary depending on the specific cause of the issue and labor rates in your area. On average, the repair cost for this type of transmission problem can range from $200 to $800, including parts and labor. However, in some cases where extensive transmission repairs are needed, the cost can exceed $1000. It's recommended to consult with a professional mechanic for an accurate estimate based on your vehicle's make and model.

What does this mean?

Tech Notes for P0742 GMC

When a transmission solenoid is stuck on, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommended to change the transmission fluid and if possible, remove the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure, and that the transmission will need to be rebuilt or replaced.

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Information for Specific GMC Models

  • P0742 2014 GMC Sierra — Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance
  • P0742 2015 GMC Sierra — Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance
  • P0742 2016 GMC Sierra — Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance
  • P0742 2017 GMC Sierra — Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance
  • P0742 2018 GMC Sierra — Torque Converter Clutch System Stuck On Or Transmission Hydraulic/Mechanical Performance
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.

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