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P066D 2018 Chevrolet Silverado Code - Cylinder 2 Glow Plug Control Circuit High Voltage

Quick Answer

The P066D diagnostic trouble code (DTC) in a 2018 Chevrolet Silverado indicates a problem with the cylinder 2 glow plug control circuit having high voltage. Common causes include Faulty glow plug in cylinder 2, Malfunctioning glow plug control module, Damaged wiring or connectors in the glow plug 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
P066D 2018 Chevrolet Silverado indicates Cylinder 2 Glow Plug Control Circuit High Voltage.
Common causes
Common causes include Faulty glow plug in cylinder 2, Malfunctioning glow plug control module, Damaged wiring or connectors in the glow plug 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 25, 2024
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Code P066D 2018 Chevrolet Silverado Description

The P066D diagnostic trouble code (DTC) in a 2018 Chevrolet Silverado indicates a problem with the cylinder 2 glow plug control circuit having high voltage. Glow plugs are essential components in diesel engines that help with cold starts by heating the combustion chamber. When the engine is cold, the glow plug control module sends a signal to the glow plugs to heat up. In this case, the high voltage in the cylinder 2 glow plug control circuit suggests an issue with the electrical system that controls the glow plug in cylinder 2.

OBDII Code P066D 2018 Chevrolet Silverado - Cylinder 2 Glow Plug Control Circuit High Voltage
P066D 2018 Chevrolet Silverado Code - Cylinder 2 Glow Plug Control Circuit High Voltage

Common Causes of P066D 2018 Chevrolet Silverado

  1. Faulty glow plug in cylinder 2.
  2. Malfunctioning glow plug control module.
  3. Damaged wiring or connectors in the glow plug circuit.
  4. Problem with the engine control module (ECM).
  5. Corrosion or poor connections in the electrical system.

Symptoms of P066D 2018 Chevrolet Silverado

  1. Difficulty starting the engine, especially in cold weather.
  2. Rough idling or misfiring.
  3. Reduced engine power and acceleration.
  4. Decreased fuel efficiency.
  5. Increased emissions.

How to Fix P066D 2018 Chevrolet Silverado

  1. Begin by diagnosing the specific cause of the high voltage in the cylinder 2 glow plug control circuit using a diagnostic scanner.
  2. Inspect the glow plug in cylinder 2 to determine if it is functioning properly or needs replacement.
  3. Check the glow plug control module and wiring for any damage or loose connections.
  4. Test the engine control module (ECM) to ensure it is sending the correct signals to the glow plug circuit.
  5. Replace any faulty components, such as the glow plug, control module, or wiring, and clear the DTC to reset the system.

Cost to Fix P066D 2018 Chevrolet Silverado

The typical repair costs for addressing a P066D code in a 2018 Chevrolet Silverado can vary depending on the specific cause of the issue. Generally, replacing a glow plug can cost between $50 and $150 per plug, while a glow plug control module may range from $100 to $300. Labor costs can add an additional $100 to $300, depending on the shop's hourly rates and the complexity of the repair. Overall, the total repair cost for this issue could range from $200 to $800. It's advisable to consult with a trusted mechanic or dealership for a more accurate estimate based on your vehicle's specific needs and location.

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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.

Frequently Asked Questions about P066D 2018 Chevrolet Silverado Code

1. What does the OBDII code P066D mean on a 2018 Chevrolet Silverado?

P066D indicates a "Cylinder 2 Glow Plug Control Circuit High Voltage," which means the glow plug circuit for cylinder 2 is experiencing a voltage level higher than expected.

2. What are the common symptoms of code P066D in a 2018 Silverado?

Symptoms may include difficulty starting the engine in cold conditions, reduced engine performance, an illuminated check engine light, and possibly rough idling.

3. What causes the P066D code to appear in a 2018 Chevrolet Silverado?

Common causes include a faulty glow plug, damaged glow plug control module, wiring issues like corrosion or shorts, or a malfunctioning PCM (powertrain control module).

4. Can I still drive my 2018 Silverado with the P066D code active?

While the truck may still run, driving with this code is not recommended, especially in cold weather, as it could lead to starting issues or further damage to the engine.

5. How do I diagnose the P066D code on a 2018 Silverado?

Start by inspecting the glow plug and wiring for cylinder 2 for signs of damage. Test the glow plug's resistance and check for proper voltage at the glow plug connector using a multimeter.

6. How can I fix the P066D code on my 2018 Chevrolet Silverado?

Repairs may include replacing the faulty glow plug, repairing damaged wiring or connectors, replacing the glow plug control module, or reprogramming/updating the PCM if necessary.

7. How much does it cost to fix a P066D code on a 2018 Silverado?

Costs can vary, but replacing a glow plug typically ranges from $100 to $300, while replacing the glow plug control module or repairing wiring may cost more depending on labor rates and parts availability.

8. Can a bad glow plug cause the P066D code on a 2018 Chevrolet Silverado?

Yes, a bad or failing glow plug in cylinder 2 is a common cause of the P066D code.

9. Will clearing the P066D code fix the issue on my 2018 Silverado?

Clearing the code will turn off the check engine light temporarily, but if the underlying issue isn’t resolved, the code will likely return.

10. Does the P066D code affect emissions in a 2018 Silverado?

Indirectly, yes. A malfunctioning glow plug can lead to incomplete combustion, which may increase emissions over time.

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