Engine-CodesGMC – P0842 2018 GMC Sierra

P0842 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 1 Circuit Low Voltage

Quick Answer

The P0842 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the Transmission Fluid Pressure Switch 1 Circuit, specifically a low voltage issue. Common causes include Faulty transmission fluid pressure switch, Damaged wiring or connectors in the 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
P0842 2018 GMC Sierra indicates Transmission Fluid Pressure Switch 1 Circuit Low Voltage.
Common causes
Common causes include Faulty transmission fluid pressure switch, Damaged wiring or connectors in the 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.
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code P0842 2018 GMC Sierra Description

The P0842 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the Transmission Fluid Pressure Switch 1 Circuit, specifically a low voltage issue. This switch is responsible for monitoring the fluid pressure within the transmission and sending signals to the vehicle's computer system. When the voltage detected by the switch falls below the specified threshold, the P0842 code is triggered.

OBDII Code P0842 2018 GMC Sierra - Transmission Fluid Pressure Switch 1 Circuit Low Voltage
P0842 2018 GMC Sierra Code - Transmission Fluid Pressure Switch 1 Circuit Low Voltage

Common Causes of P0842 2018 GMC Sierra

  1. Faulty transmission fluid pressure switch
  2. Damaged wiring or connectors in the circuit
  3. Low transmission fluid levels
  4. Malfunctioning transmission control module
  5. Internal transmission issues

Symptoms of P0842 2018 GMC Sierra

  1. Rough or delayed shifting between gears
  2. Transmission slipping or jerking during acceleration
  3. Illumination of the Check Engine Light
  4. Transmission overheating
  5. Reduced fuel efficiency

How to Fix P0842 2018 GMC Sierra

  1. Begin by conducting a thorough diagnostic scan to confirm the P0842 code and identify any other related issues.
  2. Inspect the transmission fluid pressure switch and its wiring for any signs of damage or corrosion. Replace the switch if necessary.
  3. Check the transmission fluid level and top up if low. Perform a transmission fluid flush and filter replacement if needed.
  4. Test the transmission control module for proper function and replace if faulty.
  5. Clear the DTC and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0842 2018 GMC Sierra

The typical repair costs for addressing a P0842 code on a 2018 GMC Sierra can range from $150 to $500, depending on the specific cause of the issue and the required repairs. This estimate includes the cost of parts such as a new transmission fluid pressure switch, wiring repairs, transmission fluid, and potentially a transmission control module. Labor costs can vary based on the shop's hourly rates and the complexity of the repair process. It is recommended to obtain quotes from multiple auto repair shops to find the best price for the necessary repairs.

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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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