How To Fix P0304 Code For Ford Vehicles (Meaning, Symptoms, Cost of Repair)


Do you know how to fix a P0304 Code for Ford vehicles and what are the symptoms, the causes, the estimated cost of repair? this is one of the questions our readers ask a lot. Well, we´ve got you covered.

The problem with the dreaded P0304 code is that it could mean a variety of different things, many of which are difficult to lock down without hooking your Ford up to a computer.

Of course, unless you have your own diagnostic system, that’ll cost you.

The code P0304, boiled down to its essential meaning, is a warning that your Ford vehicle had a misfire in cylinder 4. The problem lies in what caused the misfire, how to locate it, what were the symptoms, and how much it’s going to cost to fix it. 

The P0304 code is pretty common and it doesn’t spell immediate disaster for your car. Depending on the cause and fix, your car may be drivable for another 10,000 miles.

However, it’s certainly not a code worth ignoring, because it could cause a cascade effect. 

Meaning Of The P0304 Code

The P0304 code doesn’t pop up because of the myriad number of issues that could have caused a misfire in cylinder 4.

It’s the misfire itself that causes the code. If you own an OBD2 scanner, you can discover the codes on your own.

The nature of a cylinder misfire is a cylinder that stops producing power through combustion, usually for only a moment or two.

It’s called a misfire because it misfires, not because it fails altogether. 

Symptoms Of A P0304 Code/Cylinder 4 Misfire

The first and most obvious symptom of a cylinder misfire is a check engine light. A slight misfire is usually more than enough to trigger a code.

If the check engine light happens to be flashing, that’s a bad sign, often meaning there is an imminent failure. 

  • The engine is running rough, shaking, stuttering.
  • Loss of power
  • Fuel odor is obvious and originates from the exhaust
  • Jerking or hesitation when trying to accelerate
  • Trouble during start-up

All of those symptoms sound pretty ominous, however, sometimes it may be so subtle that you don’t even feel it.

All you’ll have to go on is the check engine light.

That’s why it’s important to get it checked out as soon as possible.

Diagnosing A P0304 Code

If you own a particularly sophisticated OBD2 scanner, as they have at an auto repair shop, you can lock down the specific cause of the misfire. 

  • FIXD: An OBD2 scanner that interacts with a mobile app to not only tell you the code but the problems behind the code.
  • Innova CarScan Pro:  Tells you the severity level of the code, along with other diagnostics and repair suggestions.
  • ThinkScan : This is what you’ll see the auto repair mechanic with. There’s no need for an app, as everything is laid out on the device’s screen.

OBD2 scanners aren’t cheap, however, when you’re dealing with a $50 charge just for the mechanic to hook it up and scan your vehicle, the long-term savings become pretty apparent. 

If you are a DIY mechanic or, at least a burgeoning DIY mechanic, your own OBD2 scanner is essential.

If your Ford throws a P0304 code, you’ll know what it is and, at the very least, you’ll be pointed in the right direction to get it fixed.

Estimated Cost Of Repair

The estimated cost of repair is ambiguous because it really depends on what is wrong. The P0304 code isn’t an all-encompassing code that carries a singular fix. 

Nine times out of ten, the repair is going to involve replacing one or more spark plugs, a coil pack, or the wiring between the two.

Fuel leaking into the exhaust, air leaks, and fueling faults round out the remainder of perpetrators behind the code. 

  • Spark Plug Replacement: $16 – $100
  • Coil Pack: Parts- $150 to $220 / Labor- $50 to $65
  • Fuel Leaking Into Exhaust: $125 -$300
  • Air Vacuum Leak: $150 to $1,000
  • Timing Chain: $400 to $1,100
  • Valve Springs: $450 to $650
  • Piston Rings: $1,500 to $3,000
  • Fuel Injector: $275 to $400

That’s quite a range, including all of the possibilities for a Ford vehicle to throw a P0304 code, and you could pay out anywhere between $16 and $3,000. 

Of course, using your own OBD2 scanner and locking down the exact cause of the misfire—assuming you know how to fix it—could potentially save you hundreds if not thousands of dollars. 

Depending on your level of expertise, or the level of understanding you can derive from shaky YouTube videos, piston rings, valve springs, and timing chains may be off the table.

Final Word

Chances are, the P0304 code isn’t as severe as would be necessary for a $1,000 repair, or worse.

 The most important thing is to get it diagnosed, by your own means or by a professional, as soon as you get the check engine light indicator.

Too many often let the check engine light go because they don’t feel like their Ford is driving any different.

Unfortunately, this usually causes more problems than it solves. The better you prepare for an adverse code, the better off you’ll be.

Here are some of my favorite tools & equipment´s

Thank you for reading this article. I hope it helps you find the most recent and accurate technical and repair information for your car. Here are some tools that I use as an automotive technician and hope you´ll also find helpful.

There are affiliate links, so if you do decide to use any of them, I´ll earn a small commission. But in all honesty, these are the exact tools that I use and recommend to everyone, even my own family. (NO CRAP)

To see all my of most up-to-date recommendations, check out this resource that I made for you!



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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