Engine-CodesChevrolet – P0851 2018 Chevrolet Silverado

P0851 2018 Chevrolet Silverado Code - Park/Neutral Position Switch Circuit Low Voltage

Quick Answer

The diagnostic trouble code P0851 for a 2018 Chevrolet Silverado indicates a problem with the Park/Neutral Position (PNP) switch circuit being detected as low voltage. Common causes include Faulty Park/Neutral Position switch, Damaged wiring or connectors in the switch circuit, Corrosion or moisture in the switch circuit. 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 2018 Chevrolet Silverado indicates Park/Neutral Position Switch Circuit Low Voltage.
Common causes
Common causes include Faulty Park/Neutral Position switch, Damaged wiring or connectors in the switch circuit, Corrosion or moisture in the switch circuit.
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 Aug 19, 2024
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Code P0851 2018 Chevrolet Silverado Description

The diagnostic trouble code P0851 for a 2018 Chevrolet Silverado indicates a problem with the Park/Neutral Position (PNP) switch circuit being detected as low voltage. The PNP switch, also known as the neutral safety switch, is responsible for detecting the position of the gear selector (Park or Neutral) and communicating this information to the vehicle's engine control module (ECM). When the switch circuit registers low voltage, it can lead to issues with starting the vehicle, as the ECM may not receive the correct signal to engage the starter motor.

OBDII Code P0851 2018 Chevrolet Silverado - Park/Neutral Position Switch Circuit Low Voltage
P0851 2018 Chevrolet Silverado Code - Park/Neutral Position Switch Circuit Low Voltage

Common Causes of P0851 2018 Chevrolet Silverado

  1. Faulty Park/Neutral Position switch
  2. Damaged wiring or connectors in the switch circuit
  3. Corrosion or moisture in the switch circuit
  4. ECM malfunction
  5. Poor electrical connection in the circuit

Symptoms of P0851 2018 Chevrolet Silverado

  1. Difficulty starting the vehicle
  2. Inability to shift out of Park
  3. Dashboard warning light indicating transmission issue
  4. Engine stalling when shifting gears
  5. Unintended vehicle movement when parked

How to Fix P0851 2018 Chevrolet Silverado

  1. Begin by diagnosing the PNP switch circuit using a diagnostic scan tool to confirm the P0851 code.
  2. Inspect the wiring and connectors for any damage or corrosion, repairing or replacing as necessary.
  3. Test the PNP switch for proper functionality and replace if found to be faulty.
  4. Clear the trouble code from the ECM memory using the diagnostic scan tool.
  5. Test drive the vehicle to ensure the issue has been resolved and the code does not return.

Cost to Fix P0851 2018 Chevrolet Silverado

The typical repair costs for addressing a P0851 code on a 2018 Chevrolet Silverado can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor in your area. It's important to factor in additional diagnostic time and potential fees for reprogramming the ECM if needed. As labor rates can vary, it's recommended to obtain quotes from local auto repair shops for a more accurate estimate.

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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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