AutoCodes – Nissan – P0304 2003 Nissan Sentra

P0304 2003 Nissan Sentra Code - Number 4 Cylinder Misfire Detected

Quick Answer

When a misfire occurs, engine speed will fluctuate. Common causes include Faulty Spark Plug #4, Clogged or faulty Fuel Injector #4, Faulty Ignition Coil #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 2003 Nissan Sentra indicates Number 4 Cylinder Misfire Detected.
Common causes: Common causes include Faulty Spark Plug #4, Clogged or faulty Fuel Injector #4, Faulty Ignition Coil #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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 5,906

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 23, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0304 2003 Nissan Sentra Description

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring. The Diagnostic Trouble Code (DTC) will be set when the Engine Control Module monitors the crankshaft speed and has detected that engine cylinder #4 is misfiring.

OBDII Code P0304 2003 Nissan Sentra - Number 4 Cylinder Misfire Detected - AutoCodes.com — P0304 2003 Nissan Sentra Code - Number 4 Cylinder Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0304 2003 Nissan Sentra?

Faulty Spark Plug #4
Clogged or faulty Fuel Injector #4
Faulty Ignition Coil #4
Fuel Injector #4 harness is open or shorted
Fuel Injector #4 circuit poor electrical connection
Ignition Coil #4 harness is open or shorted
Ignition Coil #4 circuit poor electrical connection
Insufficient cylinder 4 compression
Incorrect fuel pressure
Intake air leak

How to Fix the DTC P0304 2003 Nissan Sentra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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.

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0304 2003 Nissan Sentra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0304 2003 Nissan Sentra code?

Need more information on how to fix the P0304 2003 Nissan Sentra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0304 2003 Nissan Sentra 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 2003 Nissan Sentra Code

1. What are the common symptoms of OBDII code P0304 in a 2003 Nissan Sentra?

- The common symptoms include engine misfires, rough idling, loss of power, and an illuminated check engine light.

2. What are the possible causes of a Number 4 cylinder misfire in a 2003 Nissan Sentra?

- Potential causes can include faulty spark plugs, a malfunctioning ignition coil, clogged fuel injector, vacuum leaks, or low compression in the cylinder.

3. How can I diagnose the cause of a P0304 code in my 2003 Nissan Sentra?

- Diagnostic steps may involve checking the spark plugs, inspecting the ignition coil, testing the fuel injector, performing a compression test, and looking for vacuum leaks.

4. Can a dirty air filter contribute to a Number 4 cylinder misfire in a 2003 Nissan Sentra?

- Yes, a dirty air filter can lead to a lean air-fuel mixture, which may result in misfires in the cylinder.

5. Is it safe to drive my 2003 Nissan Sentra with a P0304 code?

- It is not recommended to drive the vehicle with a misfiring cylinder, as it can cause further damage to the engine and decrease fuel efficiency.

6. How important is it to address a P0304 code promptly in a 2003 Nissan Sentra?

- It is crucial to address the issue promptly to prevent potential damage to the catalytic converter and other engine components.

7. Can bad gasoline quality cause a Number 4 cylinder misfire in a 2003 Nissan Sentra?

- Poor quality gasoline or contaminated fuel can contribute to misfires, so it's important to use high-quality fuel from reputable sources.

8. Are there any simple maintenance tips to prevent a P0304 code in a 2003 Nissan Sentra?

- Regularly maintaining the ignition system, changing spark plugs on time, and ensuring a clean air filter can help prevent cylinder misfires.

9. How much does it typically cost to repair a Number 4 cylinder misfire in a 2003 Nissan Sentra?

- The cost of repair can vary depending on the cause of the misfire, but it may range from $100 to $500 or more, including parts and labor.

10. Can a DIY enthusiast fix a P0304 code in a 2003 Nissan Sentra, or is professional help recommended?

- While some simple maintenance tasks can be done by DIY enthusiasts, diagnosing and repairing complex issues related to a P0304 code may require professional help to ensure proper resolution.