2005 s60 P0300 code

asummers · Post by **asummers** » 16 Jan 2016, 18:38

Our S60 is running rough, and has a code of P0300 Random/Multiple Cylinder Misfire Detected. It had this same code last year, and I replaced all the spark plugs, cleared the code, and it ran fine. Now it is back. What could cause the fouling of the plugs? The plugs I took out were Volvo brand 3 electrode versions. I replaced them with Autolite double platinum plugs.

asummers · Post by **asummers** » 16 Jan 2016, 19:32

I looked at the old Volvo plugs I took out, and each tip was white. I took out one of the Autolite plugs, and its entire electrode is white.

asummers · Post by **asummers** » 17 Jan 2016, 12:53

I replaced the spark plugs with some very nice ($$$$$) NGK platinum plugs. And that wasn't the problem. And it back fires if you throttle it up an let off while sitting in park. And on my test drive when I slowed down to turn in my driveway, it died. Started right back up. And the multiple misfire code is back. Not having fun.

JudgeRat · Post by **JudgeRat** » 18 Jan 2016, 14:57

How are your coils?

asummers · Post by **asummers** » 19 Jan 2016, 10:13

I took it to my mechanic. I will try and remember to post what he finds.