P0304 error code 2006 PT Cruiser Touring Ed

The engine light came on 2 days ago, had it looked at today and the error code p0304 “cylinder number four misfire” was diagnosed. What causes that and what do you think would need to be done to fix that problem?

Usually a bad coil or worn out plug.

I agree. I had this same code on a 2005 Dodge Dakota and it turned out to be bad gas.

How many miles on your PT ? And which engine ? The base engine had 30000 mile plugs and the Turbo had 100000 mile plugs. The upper intake manifold has to be unbolted to replace the plugs or wires. The manuals tell you to unbolt and remove a lot of things but on my 2004 I was simply able to remove the 5 bolts that hold the front of the upper manifoldlift the front of the manifold and hang it from a bungee cord and change the plugs and wires.

There are almost 120,000 miles on the car. Not sure about the engine–know it has 4 cylinders. One other important thing is that the diagnosis included that the compression was low on cylinder 4. Mechanic said that he was 99% sure it is a valve problem, although he did not verify that visually in the engine. Thoughts?

If the compression is low on that cylinder then you’re looking at somewhat expensive engine work.
There’s no sense in throwing spark plugs, coils, or anything else at it until the compression issue is resolved as low compression can kill off a new spark plug which in turn can take out the coil.

A 120k miles is a little young to experience a cylinder head valve problem unless there are contributing circumstances such as past overheating, EGR or knock sensor system faults, etc, etc.

Cylinder head work then leads to another question about whether or not the timing belt service is up to date.

My parents are PT fans (I’m not, but I always listen when they talk). I’m pretty sure the Touring Edition had the 2.4, 4-cylinder in it. The 2 door version had turbo as an option.

All PTs except the base model had the turbo as an option. The only 2 door was the convertible.

I would want to know what the low compression reading is based on. Was it a compression test or a computer reading. A computer reading is not going to show the same cylinder pressure on a running engine cylinder, if that cylinder is misfiring.

The timing belt and water pump were replaced two months ago.