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Engine-Codes – GMC – P0304 2016 GMC Sierra

P0304 2016 GMC Sierra Code - Cylinder 4 Misfire Detected

Quick Answer

The diagnostic trouble code P0304 for a 2016 GMC Sierra indicates that there is a misfire detected in cylinder 4 of the engine. Common causes include Faulty spark plug in cylinder 4, Failed ignition coil in cylinder 4, Clogged fuel injector in cylinder 4. 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
P0304 2016 GMC Sierra indicates Cylinder 4 Misfire Detected.
Common causes
Common causes include Faulty spark plug in cylinder 4, Failed ignition coil in cylinder 4, Clogged fuel injector in cylinder 4.
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 15, 2024
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Code P0304 2016 GMC Sierra Description

The diagnostic trouble code P0304 for a 2016 GMC Sierra indicates that there is a misfire detected in cylinder 4 of the engine. This means that the fuel-air mixture in the cylinder is not igniting properly, leading to a loss of power, rough idle, and potential damage to the catalytic converter over time. A misfire can be caused by a variety of issues, including problems with the ignition system, fuel system, or engine mechanical components.

OBDII Code P0304 2016 GMC Sierra - Cylinder 4 Misfire Detected
P0304 2016 GMC Sierra Code - Cylinder 4 Misfire Detected

Common Causes of P0304 2016 GMC Sierra

  1. Faulty spark plug in cylinder 4
  2. Failed ignition coil in cylinder 4
  3. Clogged fuel injector in cylinder 4
  4. Low compression in cylinder 4
  5. Vacuum leak affecting cylinder 4

Symptoms of P0304 2016 GMC Sierra

  1. Loss of power
  2. Rough idle
  3. Engine vibration
  4. Decreased fuel efficiency
  5. Check engine light illuminated

How to Fix P0304 2016 GMC Sierra

  1. Begin by diagnosing the specific cause of the misfire in cylinder 4, such as testing the spark plug, ignition coil, fuel injector, compression, and checking for vacuum leaks.
  2. Replace the faulty spark plug in cylinder 4 if it is found to be the cause of the misfire.
  3. If the ignition coil in cylinder 4 is faulty, replace it with a new one.
  4. Clean or replace the clogged fuel injector in cylinder 4 to ensure proper fuel delivery.
  5. Address any issues with low compression in cylinder 4, such as worn piston rings or damaged valves, to resolve the misfire.

Cost to Fix P0304 2016 GMC Sierra

The cost of repairing a cylinder 4 misfire in a 2016 GMC Sierra can vary depending on the specific cause of the issue. On average, the cost of replacing a spark plug or ignition coil can range from $50 to $200 per part, while cleaning or replacing a fuel injector may cost between $50 and $300. If the misfire is due to low compression, the repair costs can be higher, potentially ranging from $500 to $1500 or more. Labor costs at auto repair shops typically range from $80 to $150 per hour, so the total repair bill can add up quickly. It is advisable to consult with a professional mechanic to get an accurate estimate based on the specific diagnosis and repair needed for your vehicle.

What does this mean?

Tech Notes for P0304 2016 GMC Sierra

The P0304 code means that cylinder 4 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 4. 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 P0304

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 P0304 2016 GMC Sierra code?

Need more information on how to fix the P0304 2016 GMC Sierra code? Get Access to Factory Service Manuals

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Get the P0304 2016 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 P0304 2016 GMC Sierra Code

1. What does the OBDII code P0304 mean on a 2016 GMC Sierra?

P0304 indicates a cylinder 4 misfire, meaning the engine's fourth cylinder is not firing properly, causing performance and efficiency issues.

2. What are the symptoms of a P0304 code on a 2016 GMC Sierra?

Common symptoms include rough idling, reduced engine performance, poor fuel economy, hesitation during acceleration, and a flashing or steady check engine light.

3. What are the common causes of a P0304 code on a 2016 GMC Sierra?

Potential causes include a faulty spark plug, a bad ignition coil, a clogged fuel injector, a vacuum leak, low cylinder compression, or issues with the engine control module (ECM).

4. Can I drive my 2016 GMC Sierra with a P0304 code?

Driving with a P0304 code is not recommended as it may lead to further engine damage, reduced fuel efficiency, and potential safety risks.

5. How do I diagnose the P0304 code on a 2016 GMC Sierra?

Start by inspecting the spark plug, ignition coil, and fuel injector for cylinder 4. Then check for vacuum leaks, low compression, or wiring issues.

6. How do I fix a P0304 code on my 2016 GMC Sierra?

Repairs may include replacing the cylinder 4 spark plug or ignition coil, cleaning or replacing the fuel injector, fixing vacuum leaks, or addressing low compression.

7. How much does it cost to fix a P0304 code on a 2016 GMC Sierra?

Costs vary depending on the issue, but spark plug or ignition coil replacement typically ranges from $100 to $300, while injector or engine repairs may be more expensive.

8. Can a dirty air filter cause a P0304 code on my 2016 GMC Sierra?

While unlikely, a severely clogged air filter might contribute to misfires by restricting airflow and affecting engine performance.

9. What tools do I need to troubleshoot a P0304 code on a 2016 GMC Sierra?

A basic OBDII scanner, multimeter, spark plug socket, and compression tester are commonly used tools for diagnosing this code.

10. How can I prevent the P0304 code on my 2016 GMC Sierra from occurring again?

Regular maintenance, such as replacing spark plugs and ignition components on schedule, using quality fuel, and cleaning the fuel system, can help prevent future misfires.

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