AutoCodes – Infiniti – P0303 2003 Infiniti G35

P0303 2003 Infiniti G35 Code - Number 3 Cylinder Misfire Detected

Quick Answer

When a misfire occurs, engine speed will fluctuate. Common causes include Faulty Spark Plug #3, Clogged or faulty Fuel Injector #3, Faulty Ignition Coil #3. 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: P0303 2003 Infiniti G35 indicates Number 3 Cylinder Misfire Detected.
Common causes: Common causes include Faulty Spark Plug #3, Clogged or faulty Fuel Injector #3, Faulty Ignition Coil #3.
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 9,396

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 Mar 29, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0303 2003 Infiniti G35 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 #3 is misfiring.

OBDII Code P0303 2003 Infiniti G35 - Number 3 Cylinder Misfire Detected - AutoCodes.com — P0303 2003 Infiniti G35 Code - Number 3 Cylinder Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0303 2003 Infiniti G35?

Faulty Spark Plug #3
Clogged or faulty Fuel Injector #3
Faulty Ignition Coil #3
Fuel Injector #3 harness is open or shorted
Fuel Injector #3 circuit poor electrical connection
Ignition Coil #3 harness is open or shorted
Ignition Coil #3 circuit poor electrical connection
Insufficient cylinder 3 compression
Incorrect fuel pressure
Intake air leak

How to Fix the DTC P0303 2003 Infiniti G35?

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 P0303 code means that cylinder #3 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 #3. If the problem persists more tests need to be done to diagnose the problem. See "Possible Causes" for the most common problems.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0303 2003 Infiniti G35 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 P0303 2003 Infiniti G35 Code

1. What does the OBDII code P0303 mean on a 2003 Infiniti G35?

P0303 indicates a misfire has been detected in cylinder number 3 of your engine.

2. What are the symptoms of a P0303 code in a 2003 Infiniti G35?

Common symptoms include rough idling, engine hesitation, reduced fuel efficiency, loss of power, and the Check Engine Light illuminating.

3. What causes a P0303 code on a 2003 Infiniti G35?

Possible causes include a faulty spark plug, bad ignition coil, clogged fuel injector, low cylinder compression, or vacuum leaks.

4. Can driving with a P0303 code damage my 2003 Infiniti G35?

Yes, prolonged driving with a misfire can damage the catalytic converter and other engine components, so itâ€™s best to address the issue promptly.

5. How do I diagnose a P0303 code on my Infiniti G35?

Start by inspecting the spark plug and ignition coil in cylinder 3. Then, check the fuel injector, vacuum hoses, and perform a compression test if needed.

6. How do I fix a P0303 code on a 2003 Infiniti G35?

Repairs may involve replacing the faulty spark plug, ignition coil, or fuel injector, addressing vacuum leaks, or repairing engine mechanical issues.

7. Can a dirty fuel injector cause P0303 in a 2003 Infiniti G35?

Yes, a clogged or malfunctioning fuel injector can lead to a misfire in cylinder 3, triggering the P0303 code.

8. How much does it cost to fix a P0303 code on an Infiniti G35?

Costs vary depending on the cause, but replacing a spark plug or ignition coil typically costs $100â€“$300, while more extensive repairs like addressing compression issues can be more expensive.

9. Can bad fuel cause a P0303 code in a 2003 Infiniti G35?

Bad or contaminated fuel can contribute to misfires, so using high-quality fuel is important to prevent such issues.

10. How can I prevent a P0303 code from recurring on my Infiniti G35?

Regular maintenance, including timely spark plug replacements, fuel injector cleaning, and checking for vacuum leaks, can help prevent cylinder misfires.