Engine-CodesGMC – P066A 2014 GMC Sierra

P066A 2014 GMC Sierra Code - Cylinder 1 Glow Plug Control Circuit Low Voltage

Quick Answer

The diagnostic trouble code P066A for a 2014 GMC Sierra indicates an issue with the Cylinder 1 Glow Plug Control Circuit experiencing low voltage. Common causes include Faulty glow plug in Cylinder 1, Wiring issues in the glow plug control 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
P066A 2014 GMC Sierra indicates Cylinder 1 Glow Plug Control Circuit Low Voltage.
Common causes
Common causes include Faulty glow plug in Cylinder 1, Wiring issues in the glow plug control 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 17, 2024
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Code P066A 2014 GMC Sierra Description

The diagnostic trouble code P066A for a 2014 GMC Sierra indicates an issue with the Cylinder 1 Glow Plug Control Circuit experiencing low voltage. Glow plugs are essential components in diesel engines, as they heat the combustion chamber to facilitate cold starts. When the glow plug control circuit in Cylinder 1 is not receiving sufficient voltage, it can lead to difficulties in starting the engine, reduced performance, and potential long-term damage if left unaddressed.

OBDII Code P066A 2014 GMC Sierra - Cylinder 1 Glow Plug Control Circuit Low Voltage
P066A 2014 GMC Sierra Code - Cylinder 1 Glow Plug Control Circuit Low Voltage

Common Causes of P066A 2014 GMC Sierra

  1. Faulty glow plug in Cylinder 1.
  2. Wiring issues in the glow plug control circuit.
  3. Corrosion or poor connections in the electrical system.
  4. Malfunctioning glow plug relay.
  5. Issues with the engine control module (ECM).

Symptoms of P066A 2014 GMC Sierra

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or misfiring.
  3. Decreased fuel efficiency.
  4. Increased emissions.
  5. Illumination of the check engine light.

How to Fix P066A 2014 GMC Sierra

  1. Begin by diagnosing the specific cause of the low voltage in the Cylinder 1 glow plug control circuit using a diagnostic scanner.
  2. Test the glow plug in Cylinder 1 to determine if it is functioning properly.
  3. Inspect the wiring and connections in the glow plug control circuit for any signs of damage, corrosion, or loose connections.
  4. Check the glow plug relay and ECM for any faults or malfunctions.
  5. Replace any faulty components, such as the glow plug, wiring, relay, or ECM, as needed to restore proper voltage to the glow plug in Cylinder 1.

Cost to Fix P066A 2014 GMC Sierra

The typical repair costs for addressing a Cylinder 1 Glow Plug Control Circuit Low Voltage issue in a 2014 GMC Sierra can range from $150 to $400, including parts and labor. However, it's important to note that the specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less. It's advisable to check local rates for a more precise 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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