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Engine-Codes – GMC – P0308 2014 GMC Sierra

P0308 2014 GMC Sierra Code - Cylinder 8 Misfire Detected

Quick Answer

The diagnostic trouble code P0308 for a 2014 GMC Sierra indicates that a misfire has been detected in cylinder 8 of the engine. Common causes include Faulty spark plugs or ignition coils, Clogged fuel injectors, Vacuum leaks in the intake manifold. 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
P0308 2014 GMC Sierra indicates Cylinder 8 Misfire Detected.
Common causes
Common causes include Faulty spark plugs or ignition coils, Clogged fuel injectors, Vacuum leaks in the intake manifold.
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 09, 2024
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Code P0308 2014 GMC Sierra Description

The diagnostic trouble code P0308 for a 2014 GMC Sierra indicates that a misfire has been detected in cylinder 8 of the engine. This means that the fuel-air mixture in the cylinder is not igniting properly, causing a disruption in the combustion process. This can lead to a range of issues, including poor engine performance, reduced fuel efficiency, and increased emissions. Ignoring this code can result in further damage to the engine, such as catalytic converter failure or damage to the spark plugs and ignition coils.

OBDII Code P0308 2014 GMC Sierra - Cylinder 8 Misfire Detected
P0308 2014 GMC Sierra Code - Cylinder 8 Misfire Detected

Common Causes of P0308 2014 GMC Sierra

  1. Faulty spark plugs or ignition coils
  2. Clogged fuel injectors
  3. Vacuum leaks in the intake manifold
  4. Low fuel pressure in the fuel system
  5. Engine mechanical issues, such as low compression in cylinder 8

Symptoms of P0308 2014 GMC Sierra

  1. Rough idling or vibrations while the engine is running
  2. Decreased acceleration or power when accelerating
  3. Increased fuel consumption
  4. Engine hesitation or stumbling during acceleration
  5. Illumination of the check engine light on the dashboard

How to Fix P0308 2014 GMC Sierra

  1. Begin by diagnosing the specific cause of the misfire by using a scan tool to identify any other related trouble codes and performing a visual inspection of the spark plugs, ignition coils, and fuel injectors.
  2. Replace any faulty spark plugs or ignition coils in cylinder 8, as they are common culprits for misfires.
  3. Clean or replace clogged fuel injectors to ensure proper fuel delivery to the cylinder.
  4. Check for any vacuum leaks in the intake manifold and repair as necessary to prevent excess air from entering the engine.
  5. If the issue persists, perform a compression test on cylinder 8 to check for any mechanical issues that may be causing the misfire.

Cost to Fix P0308 2014 GMC Sierra

The cost of repairing a cylinder 8 misfire in a 2014 GMC Sierra can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. On average, the cost of replacing spark plugs and ignition coils can range from $150 to $300, while cleaning or replacing fuel injectors may cost between $50 and $200. If additional repairs or diagnostics are needed, the total cost could increase. It is recommended to consult with a trusted mechanic or auto repair shop for a more accurate estimate based on the specific circumstances of the vehicle.

What does this mean?

Tech Notes for P0308 2014 GMC Sierra

The P0308 code means that cylinder 8 is misfiring or is randomly misfiring. Start by checking for intake leaks and if no leaks are found the next step is to replace the spark plugs on cylinder 8. If the problem persists more tests need to be done to diagnose the problem, see "Possible Causes".



There is a Factory Service Bulletins for All 2000-2020 Chevrolet Models:

2000-2020 Chevrolet Factory Service Bulletin OBDII Code P0308

This Factory Service Bulletin explains how this condition may be caused by significant carbon build-up on the intake and/or exhaust valves due to fuel contamination or incomplete burning of the fuel.

Need more information about the P0308 2014 GMC Sierra code?

Need more information on how to fix the P0308 2014 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0308 2014 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P0308 2014 GMC Sierra Code

1. What are the common symptoms of OBDII code P0308 in a 2014 GMC Sierra?

- Common symptoms include engine misfires, rough idling, loss of power, and potential hesitation during acceleration.

2. What are the possible causes of a cylinder 8 misfire detected in a 2014 GMC Sierra?

- Potential causes include faulty spark plugs, ignition coil issues, fuel injector problems, vacuum leaks, or a problem with the cylinder compression.

3. How can I diagnose the specific cause of a cylinder 8 misfire in my 2014 GMC Sierra?

- To diagnose the issue, you can perform a thorough inspection of the spark plugs, ignition coils, fuel injectors, and check for any vacuum leaks. Using an OBDII scanner can help pinpoint the exact cause.

4. Is it safe to continue driving my 2014 GMC Sierra with OBDII code P0308?

- It is not recommended to drive the vehicle with a misfire as it can cause further damage to the engine and emissions system. It is best to address the issue promptly.

5. What is the typical repair process for addressing a cylinder 8 misfire in a 2014 GMC Sierra?

- The repair process usually involves replacing the spark plugs, inspecting and potentially replacing the ignition coil, checking the fuel injector, and addressing any vacuum leaks.

6. Can a DIY enthusiast fix the cylinder 8 misfire detected in a 2014 GMC Sierra?

- Depending on your skill level and access to tools, some DIY enthusiasts may be able to address the issue by replacing spark plugs or ignition coils. However, more complex issues may require professional assistance.

7. How much can I expect to pay for repairing OBDII code P0308 in a 2014 GMC Sierra?

- Repair costs can vary depending on the exact cause of the misfire and local labor rates. It is advisable to get a diagnosis from a mechanic to determine the cost accurately.

8. Will resetting the OBDII code P0308 in my 2014 GMC Sierra make the issue go away?

- Resetting the code may temporarily turn off the Check Engine Light, but it will not address the underlying problem causing the misfire. The issue is likely to reoccur if not fixed.

9. Are there any preventive maintenance tips to avoid OBDII code P0308 in a 2014 GMC Sierra?

- Regularly servicing your vehicle, including changing spark plugs at recommended intervals, using quality fuel, and addressing any engine performance issues promptly, can help prevent misfires.

10. Can weather conditions affect the occurrence of a cylinder 8 misfire in a 2014 GMC Sierra?

- Extreme weather conditions, such as very cold or hot temperatures, can sometimes exacerbate existing issues that lead to misfires. Ensuring your vehicle is properly maintained can help mitigate these effects.

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