*URGENT ADVICE NEEDED*

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Hybrid Hobo, Jan 20, 2026 at 6:38 PM.

  1. Hybrid Hobo

    Hybrid Hobo Member

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    As many of you know, I've been living in my Prius for 4 years. I run the car all night for heat, a/c, and to power my devices.

    I've noticed that the engine has been quite rough when kicking on the past few nights. It's usually rough anyway, but even more so.

    Well...my check engine light came on about 45 minutes ago while sitting at a truck stop. I checked my oil and it was low...as in barely there, even though I had it changed 7 weeks ago. So I added about 2 quarts. The check engine light was still on.

    Next, plugged my OBD in. Got P0301 code, which is an engine misfire.

    Shortly after getting the code, the car started to rumble pretty badly, so I shut it off. Now, I have no heat, and it'll be in the teens tonight.

    Not sure if I should rough it tonight under the blanket while wearing all of my clothes, try turning the car on for warmth and take my chances, or leave the car parked and go to the motel a few blocks away?

    Can I damage the car further by running it (not driving) tonight?

    I had my spark plugs changed about 7 months ago, so I don't think that's the issue. From what I've read on here, it could be a simple coil problem or even a blown head gasket.

    I have a mobile mechanic coming out in the morning, but any advice you can offer now would be appreciated, because my world just fell apart within the past 60 minutes. Especially because next week will be in the single digits at night, and we might be expecting a blizzard this weekend. Time is of the essence, and I need to get this fixed in the coming day or two.

    TIA
     
    #1 Hybrid Hobo, Jan 20, 2026 at 6:38 PM
  2. BiomedO1

    BiomedO1 Senior Member

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    The spark plug could be fouled by the oil burn. If there's a blown head gasket, you really can't damage it any more. How does the coolant level look? Hydro-locking the motor can bend or break things; but with all that run-time - your probably due for another motor anyways.
    If you have a 10mm socket; try moving the coil from #1 to #3 and place #3 coil in the #1 position. That would eliminate the coil issue. If the problem moves from #1 to #3, you've got a bad coil.
    You need to check the oil and coolant level at every fill-up. The oil lamp won't turn-on until you've destroyed your engine; requiring 3+ quarts to refill. If your engine is running in the middle of the night and that oil lamp lights up and you don't notice - your looking at a new or replacement engine.

    Good Luck.....
     
    #2 BiomedO1, Jan 20, 2026 at 6:56 PM
    Last edited: Jan 20, 2026 at 7:22 PM
  3. PriusCamper

    PriusCamper Senior Member

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    Those are problems related to 2010-2015 Prius.... He has a 2008...
     
    #3 PriusCamper, Jan 20, 2026 at 7:22 PM
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  4. PriusCamper

    PriusCamper Senior Member

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    2 quarts of oil low can lead to an engine misfire code... So if you added a quart of oil and had to add a second quart, that's your problem. Otherwise, swapping postion of Ignition coils as mentioned above can help.

    I wouldn't worry about it... Gen2 Prius engines are super reliable!
     
    #4 PriusCamper, Jan 20, 2026 at 7:24 PM
  5. BiomedO1

    BiomedO1 Senior Member

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    Respectfully; it could be anything since there's a lot of hours and idle time on that engine. I can't look under the hood to see how bad it is.
     
    #5 BiomedO1, Jan 20, 2026 at 7:25 PM
  6. PriusCamper

    PriusCamper Senior Member

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    It's our job to reassure this guy with most common Gen2 problems related to a misfire code so he can try to get a decent night's sleep. I can assure you he'll get less sleep tonight because you're scaring him with total engine failure, which is rare for Gen2 Prius compared to Gen3.
     
    #6 PriusCamper, Jan 20, 2026 at 7:28 PM
  7. Tombukt2

    Tombukt2 Senior Member

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    After you get it filled with oil go for a drive around the block two or three times.... Seem ok now back parked . ?
     
    #7 Tombukt2, Jan 20, 2026 at 7:33 PM
  8. BiomedO1

    BiomedO1 Senior Member

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    OK, everything is unicorns and rainbows and I'll just stop by the pot shop to take the edge off.....
     
    #8 BiomedO1, Jan 20, 2026 at 7:34 PM
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  9. Hybrid Hobo

    Hybrid Hobo Member

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    PC, thanks buddy. You're always great with advice. I started the car to get heat. Its FREEZING inside with the car off, even being bundled up good. But it's rumbling pretty rough. Do you think I'm safe running the car all night? I would hate to turn a small/moderate issue into a major catastrophic repair.

    As I said, not sure what's up with the oil situation. I was checking it religiously in the fall every 2 weeks. No problems, oil was lasting for months. So I got lax in doing it, especially because I changed oil 7 weeks ago. Unless my eyes were at fault because it was dark outside, it was basically bone dry. Hope I didn't sieze the engine.

    I'm beside myself now.
     
    #9 Hybrid Hobo, Jan 20, 2026 at 7:39 PM
  10. PriusCamper

    PriusCamper Senior Member

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    That's great advice for everyone, really!
     
    #10 PriusCamper, Jan 20, 2026 at 7:40 PM
  11. PriusCamper

    PriusCamper Senior Member

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    We've had this conversation before... When I car camp in sub-freezing weather I use as many blankets and warm clothes as possible and wait till I wake up because its too cold and then run the heater on high until its way too hot and then turn the car off and see how long I can sleep before I wake up because its too cold. I remember one night it was 17' F out and only had to do that twice and slept really well.

    The method of leaving the car on all night with the thermostat at a specific setting will shorten the lifespan of the vehicle.

    Also read up on why Atkinson engines run rough sometimes when the engine turns off so you understand why its nothing to worry about.
     
    #11 PriusCamper, Jan 20, 2026 at 7:45 PM
  12. Hybrid Hobo

    Hybrid Hobo Member

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    Thanks. I'll read up in the coming days. My brain is fried now.

    And thanks too to everyone who chimed in.

    Hopefully the mechanic can diagnose it tomorrow

    P.S. - Had to turn the car on for heat. It rumbles rough at times, then gets smoother for a while. When it rumbles it shakes like I'm in the middle of a bad earthquake. Here's to hoping that the car makes it through the night okay

    P.P.S. - As I ending this message there was a BAD rumble. Seems like the engine is turning kicking on & off very quickly, as in every 90-120 seconds. Even with the fan setting on Low set at 69. Could be due to how cold it is outside. Not sure, I'm shot now.
     
    #12 Hybrid Hobo, Jan 20, 2026 at 8:19 PM
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