Engine-CodesGMC – P0851 2014 GMC Sierra

P0851 2014 GMC Sierra Code - Park/Neutral Position Switch Circuit Low Voltage

Quick Answer

The diagnostic trouble code P0851 in a 2014 GMC Sierra indicates a problem with the Park/Neutral Position (PNP) switch circuit, specifically a low voltage condition. Common causes include Faulty Park/Neutral Position (PNP) switch, Damaged wiring or connectors in the circuit, Corrosion or poor connections in the electrical system. 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
P0851 2014 GMC Sierra indicates Park/Neutral Position Switch Circuit Low Voltage.
Common causes
Common causes include Faulty Park/Neutral Position (PNP) switch, Damaged wiring or connectors in the circuit, Corrosion or poor connections in the electrical system.
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 19, 2024
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Code P0851 2014 GMC Sierra Description

The diagnostic trouble code P0851 in a 2014 GMC Sierra indicates a problem with the Park/Neutral Position (PNP) switch circuit, specifically a low voltage condition. The PNP switch, also known as the transmission range sensor, is a crucial component that informs the vehicle's computer about the gear position (Park, Neutral, Drive, Reverse, etc.). When the PNP switch circuit detects a low voltage, it means that there is an issue with the electrical signal being sent from the switch to the vehicle's computer.

OBDII Code P0851 2014 GMC Sierra - Park/Neutral Position Switch Circuit Low Voltage
P0851 2014 GMC Sierra Code - Park/Neutral Position Switch Circuit Low Voltage

Common Causes of P0851 2014 GMC Sierra

  1. Faulty Park/Neutral Position (PNP) switch
  2. Damaged wiring or connectors in the circuit
  3. Corrosion or poor connections in the electrical system
  4. Issues with the vehicle's computer or software
  5. Physical damage to the PNP switch due to external factors

Symptoms of P0851 2014 GMC Sierra

  1. Difficulty starting the vehicle
  2. Inability to shift out of Park
  3. Incorrect gear display on the dashboard
  4. Engine stalling when shifting gears
  5. Check Engine Light illuminated

How to Fix P0851 2014 GMC Sierra

  1. Diagnose the issue by using a scan tool to read the trouble codes and test the PNP switch circuit for voltage irregularities.
  2. Inspect the wiring and connectors for any signs of damage, corrosion, or poor connections. Repair or replace as necessary.
  3. Test the PNP switch itself for proper operation. Replace the switch if it is found to be faulty.
  4. Clear the trouble codes from the vehicle's computer and perform a test drive to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be required to pinpoint the exact cause of the low voltage condition.

Cost to Fix P0851 2014 GMC Sierra

The typical repair costs for addressing a P0851 code in a 2014 GMC Sierra can vary depending on the specific cause of the issue. In general, replacing a faulty Park/Neutral Position (PNP) switch can cost between $150 and $300, including parts and labor. However, if the problem is related to wiring or connectors, the repair costs may be slightly higher due to the additional labor involved in diagnosing and fixing the electrical components.

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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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