Engine-CodesGMC – P0850 2018 GMC Sierra

P0850 2018 GMC Sierra Code - Park/Neutral Position Switch Circuit

Quick Answer

The P0850 diagnostic trouble code (DTC) for the 2018 GMC Sierra relates to the Park/Neutral Position (PNP) switch circuit. Common causes include Damaged or corroded wiring in the PNP switch circuit, Faulty Park/Neutral Position (PNP) switch, Issues with the transmission control module. 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
P0850 2018 GMC Sierra indicates Park/Neutral Position Switch Circuit.
Common causes
Common causes include Damaged or corroded wiring in the PNP switch circuit, Faulty Park/Neutral Position (PNP) switch, Issues with the transmission control module.
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 11, 2024
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Code P0850 2018 GMC Sierra Description

The P0850 diagnostic trouble code (DTC) for the 2018 GMC Sierra relates to the Park/Neutral Position (PNP) switch circuit. The PNP switch, also known as the transmission range sensor or neutral safety switch, is responsible for detecting the gear shifter's position, indicating whether the vehicle is in Park, Neutral, Drive, Reverse, or other gear positions. This information is crucial for the vehicle's onboard computer to properly control various systems, such as starting the engine, engaging the transmission, and activating safety features like the backup lights.

OBDII Code P0850 2018 GMC Sierra - Park/Neutral Position Switch Circuit
P0850 2018 GMC Sierra Code - Park/Neutral Position Switch Circuit

Common Causes of P0850 2018 GMC Sierra

  1. Damaged or corroded wiring in the PNP switch circuit
  2. Faulty Park/Neutral Position (PNP) switch
  3. Issues with the transmission control module
  4. Poor electrical connections in the circuit

Symptoms of P0850 2018 GMC Sierra

  1. Difficulty starting the vehicle, particularly in Park or Neutral
  2. Engine starting in gear instead of Park or Neutral
  3. Transmission shifting erratically or harshly
  4. Vehicle stalling unexpectedly while driving

How to Fix P0850 2018 GMC Sierra

  1. Begin by conducting a thorough diagnostic scan to retrieve the trouble codes and verify the P0850 code.
  2. Inspect the wiring harness and connections related to the PNP switch for any signs of damage or corrosion. Repair or replace as necessary.
  3. Test the Park/Neutral Position (PNP) switch for proper functionality using a multimeter or scan tool. Replace the switch if it fails the test.
  4. Check the transmission control module for any faults or programming issues. Perform any necessary reprogramming or replacement.
  5. Clear the DTCs from the vehicle's computer memory and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0850 2018 GMC Sierra

The typical repair costs for addressing the P0850 code on a 2018 GMC Sierra can range from $150 to $400, depending on the extent of the repairs needed and the cost of parts. This estimate includes the cost of a new Park/Neutral Position (PNP) switch, wiring repairs, and labor charges. Additionally, it's important to factor in the cost of diagnostic testing and any additional parts that may be required during the repair process.

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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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