How To Fix P0304 Code for Nissan Vehicles (Meaning, Causes, Symptoms, Diagnosis, Cost of Repair)

P0304 Code nissan

If you are the owner of a Nissan Altima, Versa, Murano, Sentra, Maxima, Rogue, or Pathfinder model, you may at some point receive a P0304 code. This vehicle service code is indicative of an engine malfunction related to misfiring cylinders.

This is a serious engine issue that derives from various diagnoses related to different engine parts. 

In this article, we’ll explain what exactly the P0304 code signifies, as well as the causes and symptoms of this code. We’ll also discuss the different associated diagnoses of the code, as well as the estimated cost to make proper repairs.

Read on to learn about how to get your Nissan back into good condition by fixing the P0304 error.

Meaning of the P0304 Code for Nissan

As mentioned, the P0304 vehicle code in a Nissan vehicle is an issue of misfiring engine cylinders. In particular, this code relates to cylinder 4 (hence, the “4” in the code).

Engine malfunctions are always a serious matter that car owners should not take lightly. 

A bad engine or bad engine parts can lead to power issues, backfiring when you start your vehicle, poor performance, or worse. Leaving this issue unattended can become dangerous for you when driving. 

In order to remedy the issue of the P0304 code on a Nissan vehicle, you’ll need to assess the particular cause based on symptoms your car is exhibiting.

Then, you can get the issue diagnosed and repaired. 

Causes of the P0304 Code in a Nissan

Most commonly, the cause of this code in a Nissan is an issue with faulty or damaged spark plugs, ignition coils, fuel injector parts, air leaks, and fuel pressure sensors.

Issues related to fuel injectors occur on fuel injector 4 – the one associated with cylinder 4. These include bad electrical connection in the circuit or an opened harness. 

Or, you may have issues with the ignition coil. Issues associated are similar to the issues you may have with the fuel injector.

Bad compression in the cylinder is also common, as well as the wrong fuel pressure, which can be due to a bad pressure sensor.

Additionally, issues with the functioning of your spark plugs or spark plug wires will lead to the P0304 code in Nissans.

Read also: How To Fix P0304 Code For Toyota Vehicles

Symptoms of the P0304 Code in a Nissan

In order to discern the cause of the P0304 code (and to notice you have a problem in the first place), you can look for some signs to reveal the issue.

Most obviously, engine-related issues will signal a check engine light (or “service engine soon” light) in your dash.

Anytime you get this warning on your vehicle, you should have your car serviced. 

Or, you might notice issues with the running or performance of your Nissan. Often, this comes in the form of bad gas mileage, or gas mileage that is lower than it usually is.

The misfiring cylinder 4 can also present in the form of a backfiring or excessively vibrating engine. If you notice these symptoms, it could be a clear indicator that the P0304 code is significant. 

Further, abnormal smells of gas or a generally abnormally running vehicle are both indicative of the P0304 code issue. 

Read also: Can A Clogged Catalytic Converter Cause A Misfire

Diagnosis of the P0304 Code Nissan

When it comes to fixing this issue, the process becomes a little more complicated. However, with the help of a skilled mechanic, you can get to the bottom of things in no time.

Diagnosing the issue may lead to one or more of several revelations. 

You may discover that your vehicle has bad spark plugs, spark plug wires that have gone bad, a vacuum leak (air leak in the engine), malfunctioning crank and cam sensors, or low compression in the engine. 

Low compression could be due to parts like valves, head gaskets, and heads that need to get replaced within the engine.

Further, vacuum leaks could be due to bad intake manifold gaskets, throttle body gaskets, and vacuum hoses. 

2003 Nissan Altima – 2.4 – P0304 – Cylinder 4 Misfire Detected >> Check out the video below:

Estimated Cost of Repair

The cost of this repair will vary depending on which Nissan vehicle you own. However, this issue commonly presents in the Nissan Altima model, so we’ll base our repair estimates on it.

It’s also important to consider the cost of repairs and replacements for different diagnoses related to the P0304 code.

Below, we’ll compare the cost of replacing different faulty engine parts that create the P0304 code in the first place. 

  • Spark Plug Replacement – costs $165 on average
  • Spark Plug Wire Replacement – costs $110 on average
  • Intake Manifold Gasket Replacement – costs $230 on average
  • Vacuum Hose Replacement – costs $100 on average
  • Camshaft Position Sensor Replacement – costs $175 on average
  • Crankshaft Position Sensor Replacement – costs $145 on average
  • Cylinder Head Replacement – costs $3750
  • Head Gasket Replacement – costs $1790


A P0304 code for a misfiring cylinder 4 in a Nissan vehicle (typically in the Altima model) is a cause for concern.

You should get this issue diagnosed and fixed as soon as possible. The average cost to replace faulty parts that cause this code issue range between $100-$4000. 

Whether there is an issue with air pressure, spark plugs, gaskets, or some other engine part, make sure to fix this issue in a timely manner.

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Jeff is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Reatta. Jeff has been creating written and video content about transportation, automotive, electric cars, future vehicles as well as new, used for more than 18 years. Jeff is based in Boulder, Colorado.

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