Engine-CodesInfiniti – P0304 2003 Infiniti G35

P0304 2003 Infiniti G35 Code - Number 4 Cylinder Misfire Detected

Quick Answer

The P0304 code indicates that the engine control module (ECM) has detected a misfire in the number 4 cylinder of the 2003 Infiniti G35. Common causes include Worn or fouled spark plugs, Faulty ignition coil in the number 4 cylinder, Clogged or malfunctioning fuel injector. 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 2003 Infiniti G35 indicates Number 4 Cylinder Misfire Detected.
Common causes
Common causes include Worn or fouled spark plugs, Faulty ignition coil in the number 4 cylinder, Clogged or malfunctioning fuel injector.
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 13, 2024
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Code P0304 2003 Infiniti G35 Description

The P0304 code indicates that the engine control module (ECM) has detected a misfire in the number 4 cylinder of the 2003 Infiniti G35. A misfire occurs when the air-fuel mixture in the cylinder fails to ignite properly, leading to a disruption in the combustion process. This can result in a lack of power, rough idling, poor fuel efficiency, and increased emissions.

OBDII Code P0304 2003 Infiniti G35 - Number 4 Cylinder Misfire Detected
P0304 2003 Infiniti G35 Code - Number 4 Cylinder Misfire Detected

Common Causes of P0304 2003 Infiniti G35

  1. Worn or fouled spark plugs
  2. Faulty ignition coil in the number 4 cylinder
  3. Clogged or malfunctioning fuel injector
  4. Vacuum leaks in the intake manifold or hoses
  5. Low compression in the number 4 cylinder

Symptoms of P0304 2003 Infiniti G35

  1. Engine misfiring or running rough
  2. Loss of power or acceleration
  3. Rough idling or shaking while the vehicle is stationary
  4. Decreased fuel efficiency
  5. Illumination of the check engine light

How to Fix P0304 2003 Infiniti G35

  1. Diagnose the specific cause of the misfire by performing a comprehensive engine inspection and using a scan tool to identify the cylinder affected.
  2. Replace the spark plugs in all cylinders, including the number 4 cylinder, if they are worn or fouled.
  3. Test and replace the ignition coil in the number 4 cylinder if it is faulty.
  4. Clean or replace the fuel injector in the number 4 cylinder if it is clogged or malfunctioning.
  5. Check for vacuum leaks in the intake manifold and hoses, repairing or replacing any damaged components as necessary.

Cost to Fix P0304 2003 Infiniti G35

The cost of repairing a misfire in the number 4 cylinder of a 2003 Infiniti G35 can vary depending on the specific cause of the issue and the labor rates at the repair shop. On average, the cost of replacing spark plugs, ignition coils, and fuel injectors can range from $200 to $500, including parts and labor. Additional costs may apply if there are other underlying issues contributing to the misfire. It is recommended to consult with a certified mechanic or auto repair shop for a more accurate cost estimate based on the vehicle's condition and the required repairs. Labor rates typically range from $80 to $150 per hour, but can vary based on location and shop rates.

Tech Notes for P0304 2003 Infiniti G35

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" for the most common problems.

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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 P0304 2003 Infiniti G35 Code

1. What does OBDII code P0304 mean for a 2003 Infiniti G35?

P0304 indicates a misfire in cylinder number 4, meaning the engine isn’t firing properly in that specific cylinder.

2. What are the common symptoms of code P0304?

Symptoms may include rough idling, reduced engine performance, poor fuel economy, difficulty starting the engine, and the Check Engine Light turning on.

3. What causes a P0304 code in a 2003 Infiniti G35?

Common causes include a faulty spark plug, bad ignition coil, clogged fuel injector, vacuum leak, low compression, or issues with the wiring or connectors.

4. Can a dirty or clogged fuel injector cause a P0304 code?

Yes, a clogged or malfunctioning fuel injector can disrupt the fuel delivery to cylinder 4, causing a misfire.

5. How do you diagnose a P0304 code?

Start by inspecting the spark plug, ignition coil, and fuel injector for cylinder 4. Check for vacuum leaks, test cylinder compression, and examine the wiring and connectors for damage.

6. Can a vacuum leak trigger a P0304 code?

Yes, a vacuum leak near cylinder 4 can cause an incorrect air-fuel mixture, leading to a misfire and triggering the code.

7. How serious is the P0304 code on a 2003 Infiniti G35?

While the vehicle may still run, ignoring the issue can cause further engine damage, reduced performance, and higher repair costs.

8. What’s the first step to fix a P0304 code?

Begin by replacing the spark plug in cylinder 4, as it’s often the simplest and most common cause of a misfire.

9. Can a faulty ignition coil cause a P0304 code?

Yes, a failing ignition coil for cylinder 4 can prevent proper spark delivery, resulting in a misfire.

10. Is it safe to continue driving with a P0304 code?

It’s not advisable. Driving with a misfire can damage the catalytic converter, worsen engine performance, and lead to more costly repairs.

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