AutoCodes – Nissan – P0304 2002 Nissan Sentra

P0304 2002 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 2002 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.

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Code Popularity 6,736

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
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Code P0304 2002 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 2002 Nissan Sentra - Number 4 Cylinder Misfire Detected - AutoCodes.com — P0304 2002 Nissan Sentra Code - Number 4 Cylinder Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0304 2002 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 2002 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.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0304 2002 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.

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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 2002 Nissan Sentra Code

1. What does the OBDII code P0304 mean for a 2002 Nissan Sentra?

P0304 indicates that the engine control module (ECM) has detected a misfire in cylinder number 4.

2. What are the common symptoms of code P0304 in a 2002 Nissan Sentra?

Symptoms include rough idling, reduced engine performance, poor fuel economy, engine hesitation, and possibly the check engine light illuminating.

3. What causes a P0304 code in a 2002 Nissan Sentra?

Common causes include faulty spark plugs, a bad ignition coil, a clogged fuel injector, low cylinder compression, or vacuum leaks near cylinder 4.

4. Can driving with a P0304 code damage my engine?

Yes, prolonged driving with a misfire can damage the catalytic converter or other engine components over time.

5. How do I fix a P0304 code on my 2002 Nissan Sentra?

Repairs may involve replacing the spark plugs, ignition coil, or fuel injector for cylinder 4, or addressing underlying issues like vacuum leaks or low compression.

6. How can I determine if the spark plug is causing the P0304 code?

Inspect the spark plug for wear, fouling, or damage. Replacing it with a new one is a simple and cost-effective first step.

7. How do I check if the ignition coil is the problem for P0304?

Swap the ignition coil from cylinder 4 with another cylinder. If the misfire moves to the swapped cylinder, the coil is faulty.

8. Can a dirty fuel injector cause the P0304 code?

Yes, a clogged or malfunctioning fuel injector can prevent proper fuel delivery to cylinder 4, leading to a misfire.

9. What should I do if Iâ€™ve replaced the spark plug and coil but still get a P0304 code?

Check for vacuum leaks, perform a compression test on cylinder 4, and inspect the fuel injector for proper operation.

10. Is it expensive to fix a P0304 code in a 2002 Nissan Sentra?

Costs vary depending on the cause. Replacing a spark plug or ignition coil is relatively inexpensive, while addressing low compression or injector issues may be more costly.