Engine-CodesChevrolet – P0304 Chevrolet

P0304 Chevrolet Code - Cylinder 4 Misfire Detected

Quick Answer

When a P0304 Chevrolet diagnostic trouble code is detected, it means that the engine control module (ECM) has identified a misfire in cylinder 4 of the vehicle's engine. Common causes include Faulty spark plugs or ignition coils, Clogged or malfunctioning fuel injector, Vacuum leaks in the intake manifold. 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 Chevrolet indicates Cylinder 4 Misfire Detected.
Common causes
Common causes include Faulty spark plugs or ignition coils, Clogged or malfunctioning fuel injector, Vacuum leaks in the intake manifold.
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 Aug 25, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0304 Chevrolet Description

When a P0304 Chevrolet diagnostic trouble code is detected, it means that the engine control module (ECM) has identified a misfire in cylinder 4 of the vehicle's engine. This misfire occurs when there is an incomplete combustion event in the cylinder, leading to a lack of power, rough idle, decreased fuel efficiency, and potential damage to the catalytic converter over time if left unresolved. The underlying mechanics that could contribute to this issue include faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, or low compression in the cylinder.

OBDII Code P0304 Chevrolet - Cylinder 4 Misfire Detected
P0304 Chevrolet Code - Cylinder 4 Misfire Detected

Common Causes of P0304 Chevrolet

  1. Faulty spark plugs or ignition coils
  2. Clogged or malfunctioning fuel injector
  3. Vacuum leaks in the intake manifold
  4. Low compression in cylinder 4
  5. Engine timing issues

Symptoms of P0304 Chevrolet

  1. Loss of power or acceleration
  2. Rough idle or engine vibrations
  3. Decreased fuel efficiency
  4. Engine hesitation or stumbling
  5. Check Engine Light illuminated on the dashboard

How to Fix P0304 Chevrolet

  1. Perform a thorough inspection of spark plugs, ignition coils, and fuel injectors in cylinder 4.
  2. Check for vacuum leaks in the intake manifold and repair as necessary.
  3. Conduct a compression test to determine if there are any issues with cylinder 4.
  4. Verify engine timing and adjust if necessary.
  5. Clear the trouble code and test drive the vehicle to ensure the misfire has been resolved.

Cost to Fix P0304 Chevrolet

The cost of repairing a P0304 Chevrolet code can vary depending on the specific cause of the misfire. On average, the repair costs for this issue range from $100 to $500, including parts and labor. However, it's important to note that diagnostic time and labor rates at auto repair shops can impact the final cost. It's recommended to consult with a mechanic to get an accurate estimate based on your vehicle's make and model.

Tech Notes for P0304 Chevrolet

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 Chevrolet code?

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

Need Help with the Code?

Get the P0304 Chevrolet code diagnosed by a professional: Find a repair shop in your area

Information for Specific Chevrolet Models

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 Chevrolet Code

1. What are the common symptoms of OBDII code P0304 (Cylinder 4 Misfire Detected) in a Chevrolet?

- Common symptoms of P0304 include rough idling, loss of power, engine vibration, and potential stalling.

2. What are some possible causes of a Cylinder 4 misfire in a Chevrolet triggering code P0304?

- Causes can include faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, low compression, or issues with the engine control module.

3. How can I diagnose the specific cause of a Cylinder 4 misfire in my Chevrolet triggering code P0304?

- Diagnose by checking spark plugs, ignition coils, fuel injectors, compression levels, vacuum leaks, and the engine control module for potential issues.

4. Can a dirty or clogged fuel injector cause a Cylinder 4 misfire in a Chevrolet resulting in code P0304?

- Yes, a dirty or clogged fuel injector can disrupt the air-fuel mixture in Cylinder 4, leading to a misfire and triggering code P0304.

5. Is it safe to drive my Chevrolet with OBDII code P0304 (Cylinder 4 Misfire Detected) present?

- It is not recommended to drive your Chevrolet with a misfire as it can cause further damage to the engine and affect overall performance.

6. Can a bad spark plug be the sole reason for OBDII code P0304 (Cylinder 4 Misfire Detected) in a Chevrolet?

- Yes, a bad spark plug in Cylinder 4 can cause a misfire and trigger code P0304, but it is essential to check other components as well.

7. How crucial is it to address OBDII code P0304 (Cylinder 4 Misfire Detected) promptly in a Chevrolet?

- It is important to address code P0304 promptly to prevent potential damage to the catalytic converter, engine components, and ensure optimal vehicle performance.

8. Are there any DIY repair tips for fixing OBDII code P0304 (Cylinder 4 Misfire Detected) in a Chevrolet?

- DIY repair tips may include checking and replacing spark plugs, ignition coils, and performing a compression test to identify and resolve the misfire issue.

9. Can a misfiring Cylinder 4 leading to code P0304 in a Chevrolet be related to a malfunctioning engine control module (ECM)?

- Yes, a malfunctioning ECM can potentially cause a misfire in Cylinder 4, triggering code P0304, so it's essential to diagnose the ECM along with other components.

10. How can I reset the OBDII code P0304 (Cylinder 4 Misfire Detected) after repairing the issue in my Chevrolet?

- You can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes to clear the stored fault code.

Discuss the causes and fixes for P0304 Chevrolet OBDII Code

  • my 2014 silverado 5.3 keeps showing codes for water in fuel and # 4 misfire ,truck vibrates and engine light blinks,this hapened about 15 months ago had dealer replace fuel injector ,been putting techron fuel conditioner in light goes off for couple of days then comes back on and blinking intermitently,where does this water come from?will have to take back to dealer and will post what the diagnosis is when fixed.

  • Interesting problem, if there was water in the fuel tank, the engine wont run at all. Please let us what they found.

  • DROPPED OFF AT DEALER THIS MORNING ,THEY WILL DIAGNOSE TOMORROW SAID THEY HAVE BEEN REPLACING THROTTLE BODYS ON SOME OF THESE ,BUT NEED TO RUN TESTS FIRST, I WILL LET YOU KNOW WHAT THEY FIND ,# 4 MISFIRE CODE HAS BEEN COMING UP WITH LIGHT BLINKING WHEN GOING UP A GRADE OR HILL AND CAN FEEL ENGINE SHAKE.

  • Chevrolet Dealer says they have to tear inside engine seems to be an internal problem on the right bank,wont know until friday hopefully what the process will be ,will keep posted.

  • Wow. Major problem then. Hopefully you get your truck back like new soon.

  • Hey buddy, so what's the verdict on your Chevy?