Engine-Codes.com
Engine-Codes – Honda – P0304 1999 Honda Civic

P0304 1999 Honda Civic Code - Cylinder Number 4 Misfire Detected

Quick Answer

The diagnostic trouble code P0304 for a 1999 Honda Civic indicates that there is a misfire detected in cylinder number 4. Common causes include Faulty spark plug in cylinder number 4, Failing ignition coil or spark plug wire, Clogged fuel injector supplying fuel to cylinder 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 1999 Honda Civic indicates Cylinder Number 4 Misfire Detected.
Common causes
Common causes include Faulty spark plug in cylinder number 4, Failing ignition coil or spark plug wire, Clogged fuel injector supplying fuel to cylinder 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 10, 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 1999 Honda Civic Description

The diagnostic trouble code P0304 for a 1999 Honda Civic indicates that there is a misfire detected in cylinder number 4. This means that the engine is not running smoothly, and there is a problem with the combustion process in that specific cylinder. When a misfire occurs, the engine may run rough, have reduced power, experience poor fuel economy, and emit higher levels of emissions.

OBDII Code P0304 1999 Honda Civic - Cylinder Number 4 Misfire Detected
P0304 1999 Honda Civic Code - Cylinder Number 4 Misfire Detected

Common Causes of P0304 1999 Honda Civic

  1. Faulty spark plug in cylinder number 4
  2. Failing ignition coil or spark plug wire
  3. Clogged fuel injector supplying fuel to cylinder 4
  4. Low fuel pressure in the fuel system
  5. Engine mechanical issues such as low compression in cylinder number 4

Symptoms of P0304 1999 Honda Civic

  1. Rough idling or vibrations while the engine is running
  2. Loss of power or acceleration
  3. Decreased fuel efficiency
  4. Engine misfires or hesitation during acceleration
  5. Check Engine Light illuminated on the dashboard

How to Fix P0304 1999 Honda Civic

  1. Begin by diagnosing the specific cause of the misfire, such as testing the spark plug, ignition coil, and fuel injector in cylinder number 4.
  2. Replace the faulty component causing the misfire, such as installing a new spark plug, ignition coil, or fuel injector.
  3. Check and adjust the ignition timing if necessary.
  4. Perform a compression test on cylinder number 4 to ensure there are no underlying engine mechanical issues causing the misfire.
  5. Clear the diagnostic trouble code from the vehicle's computer and test drive the vehicle to ensure the misfire has been resolved.

Cost to Fix P0304 1999 Honda Civic

The cost of repairing a cylinder number 4 misfire in a 1999 Honda Civic can vary depending on the specific cause of the issue and the parts and labor required for the repair. Typically, replacing a spark plug or ignition coil can cost between $50 to $200, while replacing a fuel injector may range from $150 to $300. Engine mechanical repairs, such as addressing low compression, can be more expensive, potentially costing several hundred dollars.

What does this mean?

Tech Notes for P0304 1999 Honda Civic

The P0304 code means that the 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 needs to be done to diagnose problem, see "Possible Causes"

When is the Code Detected?

Engine Cylinder 4 is Misfiring.

Need more information about the P0304 1999 Honda Civic code?

Need more information on how to fix the P0304 1999 Honda Civic code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0304 1999 Honda Civic 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 1999 Honda Civic Code

1. What are the common symptoms of a P0304 OBDII code in a 1999 Honda Civic?

- Common symptoms include engine misfiring, rough idling, loss of power, and potentially increased fuel consumption.

2. What are the possible causes of a cylinder number 4 misfire detected in a 1999 Honda Civic?

- The most common causes include faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, or low compression in the cylinder.

3. How can I diagnose the exact cause of the P0304 code in my 1999 Honda Civic?

- Diagnostic steps may include checking spark plugs, ignition coils, fuel injectors, performing a compression test, and inspecting for vacuum leaks using a smoke machine.

4. Can driving with a P0304 OBDII code in a 1999 Honda Civic cause further damage?

- Continuing to drive with a misfire can potentially lead to damage to the catalytic converter, oxygen sensors, or other engine components over time.

5. How can I repair a cylinder number 4 misfire in my 1999 Honda Civic?

- The repair may involve replacing faulty spark plugs, ignition coils, fuel injectors, addressing vacuum leaks, performing a compression test, or seeking professional help for further diagnosis.

6. Are there any maintenance tips to prevent a P0304 code in a 1999 Honda Civic?

- Regular maintenance, such as changing spark plugs, replacing ignition components at recommended intervals, and using quality fuel, can help prevent cylinder misfires.

7. Can a dirty or clogged fuel injector cause a P0304 code in a 1999 Honda Civic?

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

8. How long can I drive with a P0304 OBDII code in my 1999 Honda Civic before getting it repaired?

- It is recommended to address the issue as soon as possible to prevent potential damage to other engine components and ensure optimal performance.

9. Will resetting the OBDII system clear the P0304 code in a 1999 Honda Civic?

- Resetting the system may temporarily clear the code, but if the underlying issue causing the misfire is not addressed, the code is likely to reappear.

10. Is it possible for a faulty oxygen sensor to trigger a P0304 code in a 1999 Honda Civic?

- While less common, a faulty oxygen sensor can affect the air-fuel mixture, potentially leading to a misfire and triggering the P0304 code.

Discuss the causes and fixes for P0304 1999 Honda Civic OBDII Code

Submit a New Comment

Code P0304 1999 Honda Civic comments

No comments found for this page.