Subaru Intermittent Misfire – P0300

41 thoughts on “Subaru Intermittent Misfire – P0300”

1. I've had the same issue on my Subaru and its still doing it. I've replaced the spark plugs with NGK, plug wires with NGK, OEM coil pack, cleaned the injectors, and its still happening. Misfire is very random but always happens when I'm idling at a stop.

2. 👍🏻

3. I really love and appreciate all of your videos! I have learned alot from your knowledge and expertise. You are definitely my favorite mechanic and a realy cool person with a great sense of humor. Just wanted you to know that you are appreciated! Bill from colorado. Happy new year to you and your family.

4. Just had this issue last weekend. 2009 Subaru Forester X with 160K miles. Cold start one morning it popped P0303 & P0304 codes and idled rough/ran like crap. Had oil in spark plug tubes for cylinders 2 & 4. Changed valve cover gaskets/spark plug seals,spark plugs/wires . Ran better but had P0302 & P0304 codes. Changed ignition coil & it ran worse. Put original coil back in, it ran better but had P0303 code. Cleaned throttle body and put B12 Chemtool in gas tank with fill up. Runs like a champ again. Took 3 days of troubleshooting and time on channels like this along with some Subaru Owners forums but it was worth it. Hopefully this helps someone.

5. Great video.
   I have a 2002 Nissan Xterra 3.3 VG33e 2X4 non supercharged. Having the same sort of issue. Mine however has a distributor. My codes jump around from misfire cylinder 4 to 3 to ultiple. Check engine light only comes on if I do a cold start and just let it idle. If I start it and just drive the Check engine light never comes on. But you can feel and hear it misfire then it goes away. Could I have the same issue? I've changed plugs, wires and injectors. Still having the problem. She has 287,000 plus miles. And ideas would be greatly appreciated. Thanks

6. Old video.. nicely popped into my feed 😊😊 disclosure first..love this channel…
   Question is.. would ignition coil issue create symptoms while steady driving..kinda jerks like im letting off gas pedal or pressing it without actually doing that and this happens right after cel comes on solid not flashing. Did one evening then didn't do it for 3 days very random and the cel is off when I restart car ??? if you answer or need clarification thanks in advance

7. God bless you brother. Respect your work ethic and honesty.

8. Fire in the hole

9. Mr Frank Distress
   Hi Mr Eric O it is my first time watching your videos and i would say it is excellent in tech and knowledge. I big like and also a subscriber now, thank you. I bought my son a 2009 Subaru Impreza 2.5 non turbo with 86,000 miles. I am having the miss fire on cylinders 1 and 3, the cruise control light blinking and check engine light on. After 3 ignition coils, the mechanic is suggesting for me to buy the coil from the dealer, because he says the after market coils seems to be no good. Please any suggestion will help and thanks again.

10. Great job. Ny getn cold? Just moved to SC. Warmer but kinda miss the hudson valley.

11. i came tov the conclusion that my 2003 forester needs a coil pack a while ago and put my parts car one on it. it would loose power going long drives, up hill sometimes and all the sudden it just has a major misfire in one cylinder now. i put sparkplugs into it and didnt help, new wires but nope, threw on a fuel filter and injectors but not that either. so i am putting new 02 sensors on it cause i figured the cat was clogged since it was red hot a while back and it only has a p130 code but has set for almost a year now just couldnt figure it out. if the dam 02s dont work im getting a new coil pack and if that was it im going to be happy and pissed haha but either way everything else was done haha fml. dosent help the other parts car had the same peoblem and why the guy sold it!

12. Is it a valid conclusion that oil leaking onto one or more spark plugs, is the cause of an intake backfire under load?

13. Hi Erick
    Making great videos with Subaru and other cars ,doin fantastic job as well .
    Im owner of Subaru Ej253 Forester , 2.5L
    Having light isue when is cold in morning does misfire
    And sometimes when Revs between 1.5 k and 2.k does miss link when I let clutch ,and when is warm not missfireing
    Changed new :
    Ignition coil , map sensor , spark plugs ,New cableS as well changed throttle body / used one
    And when i scan with odb tool meter , no codes showing either

    Any opinion ?
    Big hello from downunder
    NSW Australia

14. I always drove it till it's dead. Easier to troubleshoot but tow bill and broken car laughing at me and not driveable.

15. Won't throw parts at it, as it is the customers money? the subaru just threw $3,000 parts on my car and $2,700 labor – and wanted to add in an additional $3,000 catalytic converter on to the deal…………my car was not worth all that money – I guess they were trying to nudge me into buying a new car……………nope…….I didn't win the lottery, not doing it, no matter how nice the 2021 cars are. The kids are great !

16. woopty doo for my subaru

17. Just found this channel. Bought a 99 forester three days ago it crapped out on me, shimmy shaking losing power. So here I am sitting at work watching YouTube lol. Keep up the good work. Really like the detail in the video. Keep up the good work.

18. SMA be like, no parts cannon allowed !

19. did u use a attenuator on this application could see where you probed coil but didnt see other connection

20. P0303 on my 08 Outback. Happens after car has been sitting in a very damp garage. Car bucks until it warms up and then some. Pulled #3 wire and the spark plug tube had moisture on it. Dried it off and let the plug well dry out before reassembling and it runs fine now. Would you use dielectric grease (or some other substance?) along the top neck of the tube where it seats into and "seals" up against the engine to prevent moisture making its way down the tube?

21. Awesome job as always

22. After battery reset or deleting faults, turn the ignition to the on position for 10 seconds before cranking. It allows the throttle body to learn position and prevent the extended crank

23. If I was going to try to find a shop that operates as good as Eric, How would I know they are as competent????? Help me?

24. I wish every mechanic was as honest as you

25. My 06 legacy gt's engine started to shake when i went to accelerate when i was on the highway i was going like 60 and i tried accelerating more and it started to shake then the CEL blinked like twice then went away and then came on later, what could this be?
    Also my brother checked the coils and one of them was kinda cracked, do you think it couldve been the coil?

26. good video; honest shop; must have a lot of business !!

27. I bet it's crank sensor.
    I know people will say they ether work or don't.
    But I've changed alot of crank sensors and it's fixed misfires.
    I guess the sensor gets a hair line crack that is fine till everything warms up and then it expands and interferes with the signal .
    Especially as crank sensor times the spark. 😎😉

28. I finally tracked down my misfire mishaps! Two problems: poor connection in ECM to manifold harness connector which cleaned up with contact cleaning and extra ooomph plugging it in….. after that the Cyl 3 misfire continued: Ohm-Ed it out and found open ECM wife in the manifold side of the harness. Now to isolate to wire vs plugs. I’d have loved to turn you loose on my 02 WRX wagon on this one.

29. Thank you so much. I am having this identical issue, on a 04 Impreza Outback Sport 2.5 SOHC, same thing.

30. Hey Eric, I've got a 2005 Toyota Prius II with 150k miles, it runs fine and no MIL, but it has a P0301 (sporadic). So the issue is limited to cylinder 1. Am I right to assume its most likely spark plug 1, ignition coil 1, bad wiring for cylinder 1 ignition, or a worn out (not compression) cylinder 1? Vacuum leaks, bad MAF, etc should result in more randomly spread misfires, right?

31. uga duga a naper croil might last once around the block

32. And all wires

33. Sparks need replacing on all cylinders

34. Seeing the new wires, I wonder if the old ones on that side were open and causing the coil to be overworked and get overheated causing damage to it internally.

35. Hey Eric I work on Subaru's also if u can't duplicate the miss spray water from a squirt bottle on the coil usually if it's bad it will act up right after. No need to break out the Pico.

36. Gosh darnit I just Did a Vf39 turbo swap onto my 2005 ej205 w/pink injectors and sti intercooler and now I have p303 misfire. Car idles rough and has no power, turbo will barely spool before 4k rpm. I replaced turbo inlet hose as oem one sucks and it was falling apart so I thought that would solve problem(massive vacuum leak) but same problem persists.. Anyone have any ideas. Problem was not present before swap.

37. My '06 Forester had a similar misfire problem but it would happen after big temperature changes. Found out the rubber around the spark plug wires was dried out and allowing moisture in causing the misfire. $4 tube of electrolytic grease and it runs good as "new"!

38. One! Two! Ugga-Dugga-CUE!

39. Just replaced the ignition coil on my ‘08 Forester, had rough running and code P0302. Coil looked a little crusty on wire 2 post, in fact the wire broke off. I don’t have a fancy scanner so I took a chance and replaced it (and plug wire) with parts from the junkyard. Figured I could buy 20 coils used for the price of one new. Anyway, took the car out for a toot, problem solved. Thanks Eric!

40. I had a 1982 Mercury Lynx, brand new about 500 miles and the coil was leaking oil. I took it to the garage under warrenty and the service manager told me that because it was still working, they might not be able to cover it. I blew up at him and told him so its NORMAL to leak and they ALL are supposed to leak? I told him I wanted to see his manager . What an IDIOT! The manager looked at him and said " REALLY?" JUST REPLACE IT! I had it out with that service manager again when the exhaust fell off a week later. It was defective. At first he started his crap and I said " Really? " Just like the Manager said for the coil. They replaced it. A month later I got a RECALL on it for the exhaust being defective. That was the same model that was recalled for bad headbolts. Mine never developed an issue so I never took it in. Apparently, the headbolts were supposed to stretch but didnt, so many Escorts were developing blown head gaskets or the head bolt were snapping off in the head. I put about 200k on that little car before trading it. I owned two other Escorts after that. I actually had 280k on our last Escort. I took it in to the dealer and he said it had hardly any compression left and was blown away we had put that many miles on an Escort. I had changed the timing belt twice in its life time, did countless brake jobs and many other things but that kept that Escort running up till the end of its serviceable life. The mechanic was impressed that looked at it. Came out to tell me he had never seen an Escort with that many miles and well maintained. Hey, I will take those compliments all day long.

41. Hi Eric O. I have a 97 Subaru outback and it only misfires on cylinders 2 & 4 when the temps are below 35 degrees. Misfires seems to go away during the spring summer and fall. Any thought?

Comments are closed.