Engine-CodesGMC – P0746 2018 GMC Sierra

P0746 2018 GMC Sierra Code - Transmission Control Solenoid Valve 1 Stuck Off

Quick Answer

The P0746 diagnostic trouble code (DTC) for the 2018 GMC Sierra indicates a problem with the Transmission Control Solenoid Valve 1 being stuck off. Common causes include Faulty Transmission Control Solenoid Valve 1, Wiring or connector issues, 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
P0746 2018 GMC Sierra indicates Transmission Control Solenoid Valve 1 Stuck Off.
Common causes
Common causes include Faulty Transmission Control Solenoid Valve 1, Wiring or connector issues, 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.
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code P0746 2018 GMC Sierra Description

The P0746 diagnostic trouble code (DTC) for the 2018 GMC Sierra indicates a problem with the Transmission Control Solenoid Valve 1 being stuck off. This solenoid valve is a crucial component of the transmission system, responsible for regulating the flow of transmission fluid to control gear shifting. When this solenoid valve is stuck in the off position, it can lead to various issues with the transmission's performance.

OBDII Code P0746 2018 GMC Sierra - Transmission Control Solenoid Valve 1 Stuck Off
P0746 2018 GMC Sierra Code - Transmission Control Solenoid Valve 1 Stuck Off

Common Causes of P0746 2018 GMC Sierra

  1. Faulty Transmission Control Solenoid Valve 1
  2. Wiring or connector issues
  3. Low transmission fluid levels
  4. Internal transmission damage
  5. Electrical problems in the transmission control module

Symptoms of P0746 2018 GMC Sierra

  1. Harsh or delayed shifting
  2. Erratic transmission behavior
  3. Transmission slipping
  4. Lack of power or acceleration
  5. Reduced fuel efficiency

How to Fix P0746 2018 GMC Sierra

  1. Perform a diagnostic scan to confirm the P0746 code and identify the specific issue.
  2. Inspect the Transmission Control Solenoid Valve 1 for proper operation and replace if necessary.
  3. Check and repair any wiring or connector issues related to the solenoid valve.
  4. Ensure proper transmission fluid levels and quality, topping up or replacing as needed.
  5. Clear the DTC and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix P0746 2018 GMC Sierra

The typical repair costs for addressing the P0746 code on a 2018 GMC Sierra can range from $200 to $500, including parts and labor. However, it's important to note that actual costs may vary depending on the specific diagnosis, parts required, and labor rates at auto repair shops. Diagnostic time and labor rates typically range from $80 to $150 per hour, with rates potentially higher at dealerships or in metropolitan areas. It's recommended to obtain quotes from local auto repair shops for a more accurate estimate.

Tech Notes for P0746 2018 GMC Sierra

When a transmission solenoid has malfunctioned, 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 dirty, it's 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 mechanical transmission failure, and that the transmission will need to be rebuilt or replaced.

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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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