Momentary Sputtering 2013 Prius Plug-In

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by FrugalBeeotch, Aug 15, 2025 at 6:57 PM.

  1. FrugalBeeotch

    FrugalBeeotch Junior Member

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    Hello Fellow Gen3ers!

    A few days ago, I had a momentary sputtering issue with my car. The A/C was on when I pushed the start button. After about 5 seconds, the IC kicked on, and it ran rough. I immediately turned off the A/C, but that didn't fix the problem. I pushed the gas pedal down, and the engine revved up, but I didn't floor it. The sputtering disappeared as soon as I revved up the engine. I kept it revved up for about 10 seconds. When I took my foot off the gas, the engine slowed down and ran normally. It hasn't done it again, and it drives fine.

    I've read it could be the EGR valve. Since it only happened once, I'm not sure. I'm fairly handy, and I've done basic repairs on the car before. I also have 6 hours of saved time at my local do-it-yourself garage, and I've got some money set aside for repairs.

    The car just passed 200k miles. I do oil changes about every 5,000 miles. A few years ago I had the inverter coolant changed. I've checked all the fluids, and they're all fine.

    Is this something I need to worry about? I drive over 2 mountain passes twice a week for work, and I'm worried about breaking down. Do I need to prepare to replace the EGR valve? Any other advice or guidance? This is the best car I've ever owned, and I don't want to replace it.
     
    #1 FrugalBeeotch, Aug 15, 2025 at 6:57 PM
  2. Brian1954

    Brian1954 Senior Member

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    Yes, you should be concerned if the cold rough start-up of your car happens a few times in a row. At your 200k miles, I would be more concerned that the problem is from a failing head gasket rather than the EGR valve. A failing head gasket is a farely common problem on the Gen 3 Prius. Search this forum, and you will find all the information that you need about the head gasket problem.
     
    #2 Brian1954, Aug 16, 2025 at 7:16 AM
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  3. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Probably coolant getting by head gasket, into cylinder(s), accumulating overnight.

    borescope inspection is usual next step. Keep an eye on coolant level in the reservoir till it’s resolved.

    EGR system, including intake manifold, ever been cleaned?
     
    #3 Mendel Leisk, Aug 16, 2025 at 11:00 AM
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  4. bisco

    bisco cookie crumbler

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    entertaining, merv on prius egr circuit cleaning: watch
     
    #4 bisco, Aug 16, 2025 at 2:17 PM
  5. NutzAboutBolts

    NutzAboutBolts Senior Member

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    That’s probably your early signs of a head gasket failure. Mine happened like that, then 80k miles later, misfire on cylinder 1 and low coolant.
     
    #5 NutzAboutBolts, Aug 16, 2025 at 8:04 PM
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