Code P0304

TASHALEE

MEMBER
2017 DODGE CARAVAN
3.6L
6 CYL
2WD
AUTOMATIC
72,000 MILES

So my Dodge sometimes shakes when I go past 40mph. When I take my foot off of the gas it stops shaking. I took it to AutoZone and they checked the codes and it said code P0304. The guy said it could be a vacuum leak, dirty fuel injector, bad spark plugs, or bad coils. So I don't hear any hissing so I don't think it's a vacuum problem. Idk if it is the spark plugs or coils because it's not at 100k yet. I think it may be bad fuel injector but idk how to check for that. Is there any way to check for dirty fuel injectors by myself? Would a bad roller arm cause this code? I know it does have a bad roller arm.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Welcome to 2CarPros.

Since that is the only code pulled, I don't suspect a vacuum leak. Usually a vacuum leak will cause a random misfire and not one specific cylinder.

Now, the plugs could be an issue or a plugged injector. So, here are two links. The first explains how to check for ignition spark. Check cylinder three to confirm the coil and plug are good.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Here is a link which explains how to check an injector.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

You will need some basic tooling to check both. Here are links you may find helpful.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-check-wiring

Now, the easiest way to check if a coil is bad is to simply switch it with a coil from a different cylinder. At that point, drive the vehicle until you feel the misfire and the check engine light turn on. Next, scan the computer to see if the misfire has changed cylinders. If it has, replace the bad coil. If it hasn't, then either a plug or injection issue is most likely.

Let me know if you have questions or if any of this helps.

Take care,
Joe