On and off engine light, code P0301

STICK15

MEMBER
2008 LINCOLN MKZ
3.5L
6 CYL
135,000 MILES

After the car is ran 30 minutes and more the check engine light comes on. I checked on got a p0301 error. But the engine lights goes off after a while. Car runs a little rough while engine light is on. Goes on and off intermittently.

Sunday, August 29th, 2021 AT 1:58 PM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

I suspect this could be as simple as a spark plug issue or even an injector.

The light turning on and off is basically saying that the PCM is able to see the misfire and then adjust the fuel enough to compensate for it but it eventually comes back.

If the engine runs rough all the time then the misfire normally will not just go away but the PCM is able to get it back within the parameters to turn the light off. However, it is always still there.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

What I would do is start with the spark plug and either replace it if it looks fouled like the ones in the chart below or swap it with another one from the other bank of cylinders to see if the misfire changes from cylinder 1 to that other cylinder.

If it does then you know the plugs are the issue. If it doesn't then do the same thing with the coil for that cylinder next.

If it doesn't then do the same with the injector.

Please see the info below for more detail on how to do this. Let us know what you find and we can go from there. Thanks

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