How to Diagnose Engine Code P0300 Misfire 2000-07 Volvo V70

Hi. I'm Mike with 1A Auto. We've been selling auto parts for over 30 years.

Hi, everyone. Sue here at 1A Auto. Today, we have an '03 Volvo V70 with a 2.4 liter. We're going to talk about one of the top five trouble codes. It's a PO300, 31, 32, 34, 35. It's a misfire code. What we want to talk about is, what are the top problems?

You have to access the cover. I've already taken all of the screws off. I left one in there to show you. It's a T30 Torx bit. We can take that right out.

We're going to remove the cover, so we can get to the coils. Oil filler cap has to come off, and you've got to access this, this one, and we'll put that cap right back on. We don't want anything in there. The nose of the cover for the timing cover has to come off. There are two clips. Slide that off. Now we've exposed the five coils. If you have a misfire and you haven't done maintenance, you might want to change the spark plugs and all five coils. Key being, make sure you get qualified, good-quality parts.

The top connectors on these coils are known to break free or burn out. They also have grounds in between. See the ground straps? Even though they feel tight, you want to disconnect those. Check the corrosion on them because this is aluminum on a tin cover, so you can get oxidization. You also have some ground straps back here. That's more of an engine block ground, but these grounds will feed this harness.

If you've done spark plugs and you get a misfire after you've done spark plugs, that means you disturbed the coils. Maintenance-wise, on direct ignition like this, make it a practice of doing spark plugs with the coils at the same time. Gets expensive, but it's also quality work and no step-back finding problems, conditions afterwards.

I hope that these tips help you out.

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