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Flashing Check engine light, engine running rough.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ShaneBacon, Nov 13, 2016.

  1. ShaneBacon

    ShaneBacon Junior Member

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    I have a 2008 Prius with 191k miles on it. I started the car up one afternoon and when the engine kicked on the entire car started to shake and the check engine light came on. I gave it some gas and the shaking stopped when the engine revved. I took it for a small drive and when I accelerated to get up to speed it seemed to lack power and the check engine light was flashing. I drove it the next morning and the shaking wasn't as bad and the check engine light didn't flash when accelerating. The day after that the shaking went away and the check engine light went away after a few cycles. However, now the shaking seems to come and go intermittently and seems to be at its worst when its cooler or when the engine is charging the battery. It also seems to be better when I have the heat cranked up (possibly because of higher engine RPM?).

    I'm wondering what this could possibly be. I'm planning on taking it to a mechanic or dealership soon to check it out soon so I'll post back on here if I find out anything.
     
  2. JC91006

    JC91006 Senior Member

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    Bad spark plugs or bad coil. Check those first
     
  3. jadziasman

    jadziasman Prius owner emeritus

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    The check engine light comes on whenever there is an emissions related fault - meaning that the car is not operating within the range where it spews an allowable amount of emissions (Volkswagen managed to cheat that by design).

    Seems as though you have an intermittent engine misfire, which can be fairly difficult to troubleshoot because it can be the engine itself or the emission control system that's causing it.

    The next time the check engine comes on and stays on while you're driving you should be ready to read the diagnostic trouble codes that are generated and stored. I use Torque Pro and an ELM527 bluetooth adapter on the OBDII port to constantly monitor my Prius so I can check for codes the moment any of the warning lights come on - which is not often by the way.
     
  4. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Before you go to a mechanic that you may or may not know.....read the codes that are being displayed behind the CEL.
    If you don't want to pop for a a code reader you can go to a big box parts store and they will read the codes for you.
    How to Read and Understand OBD Codes: 10 Steps (with Pictures)



    A flashing CEL (Check Engine Light) is something serious. It usually indicates that your vehicle’s engine is misfiring, which could severely damage engine TB, and catalytic converter.
    One of the faster ways to find out how much junk yards are paying for non-running cars is to continue to drive one with a flashing CEL.
    It can actually be WORSE than driving while very low on oil, since that can only wreck your engine.

    Good Luck!
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah just for giggles, if you haven't recently: check the oil level. And coolant reservoirs.
     
  6. andrewclaus

    andrewclaus Active Member

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    Ditto the advice about a flashing CEL. Stop driving the car as soon it is safe, you are doing damage.
     
  7. ShaneBacon

    ShaneBacon Junior Member

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    All of the fluid levels are okay. When I turned it on and it started doing shaking terribly, that's the first thing I did. The day before this happened I actually filled up and added some oil since it was getting low. I wouldn't think it was bad gas because it only does it when idle and seems to sound better while under load. But maybe I'm wrong.
     
    Mendel Leisk likes this.
  8. ShaneBacon

    ShaneBacon Junior Member

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    I have a scan gauge II but all it is giving me for codes is a P0000
     
  9. edthefox5

    edthefox5 Senior Member

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    How low was it? Everyone asked about the oil level because a high mileage G2 motor when run pretty close to dry will incur lower end bearing damage. It sometimes starts as a misfire code as the vibration in the engine confuses the decode of the camshaft and crank sensor
    fpg. Unexpected response to those fpg's reflect bad response to fire command and it throws a misfire code. Another words it expects certain revolutions based on ignition. If lagging it will throw a misfire code.

    Be aware the motor may be toast.

    But this engine is like any other engine. May have bad cops. Pull the spark plug cops and plugs and look at the cop boot very closely in the sun for cracks.
    See how corroded the spark plug well is as late model G2's may allow water to get past the seal on the windshield dam if that seal is bad allowing water to run onto the top of the motor and get in the spark plug wells. You can identify which cyl is misfiring by getting the codes read it is throwing. A bad bottom end will continuously change the cylinders it reports as misfiring which will confuse you.

    Go on youtube and look up Prius Inspection as there's a certain button push scenario where you can make the engine run continuously nonstop for inspection. With engine running nonstop get under the front of the car and listen to the bottom end of the motor. Listen for knocking.
    It helps if someone would push on the accelerator while braking to put the motor under load. A bad bottom end bearings will knock under load. May save you alot of time.
     
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  10. bikes4u

    bikes4u Member

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    Take it to autozone and have them check it. Sounds like your code checker knows there is something wrong but is unable to let you know what it is. How old are the spark plugs? a bad plug could cause a blown coil so could have 2 problems there
     
  11. bikes4u

    bikes4u Member

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    The way we used to check it before computers was to pull each wire ( now coil) one at a time and see which coils cause change/no change in the rough running engine. Once you narrow it down you can replace the plug and coil and see if that cures the problem.
     
  12. ShaneBacon

    ShaneBacon Junior Member

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    The oil was a little bit below halfway below the top line. Nothing that serious, I'd hope.

    I took it to my local parts store and got the codes read off of it. It had multiple Pxxxx's that said misfire on different cylinders. Then it had a C1300- Malfunction in the engine control unit. The guy at the store recommended that I take it to a dealer or someone certified to work on these kind of cars since Prii can be picky. The only problem is I live about an hour from the closest Toyota dealership.

    The funny thing is, I started up the car to take it to the store and it sounded fine. however, after letting it idle for about 20 seconds it began to make the same terrible noise and shaking. I drove it very carefully to the store and no flashing check engine light came on and it seemed OK but It didn't really feel normal. When driving home it actually sounded normal and was driving normally. After coming back from the parts store I put it into forced idle mode and it sounded perfectly normal. I have a video to show what it sounds like.

    (you can hear how it makes the sound when first starting to rev up but then it goes away at a higher rpm. it also helps to have your volume turned up)


    I also managed to get a video of the sound stopping:
     
    #12 ShaneBacon, Nov 14, 2016
    Last edited: Nov 14, 2016
  13. bikes4u

    bikes4u Member

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    doesn't sound good . If it was mine I would start by changing all spark plugs. I would also consider doing a compression check in all cylinders. After the plugs I would change out the coils. I'm not sure what is involved with changing out the ECU maybe someone else can chime in on that.

    I wouldn't drive it until it was fixed.
     
  14. edthefox5

    edthefox5 Senior Member

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    Sounds bad but the fact that the noise stops there on the second video makes me think its a bad cop or spark plug. There's a youtube about a Prius making the same noise and it had a bad cop. I wouldn't drive it till I fixed it though.
     
  15. ShaneBacon

    ShaneBacon Junior Member

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    Okay. So I pulled all of the spark plugs out and the one on the farthest right (driver side) has oil on it up to the ceramic part of the plug. I've done some research and that means a leaky gasket. How would I go about fixing this?
     
  16. jadziasman

    jadziasman Prius owner emeritus

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  17. bikes4u

    bikes4u Member

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    So you are saying that oil leaked from the engine up through the threads and onto the ceramic part of the plug?
     
  18. andrewclaus

    andrewclaus Active Member

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    I think the diagnosis is a leaking valve cover gasket.
     
  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Or a loose spark plug. Either is relatively easy to remedy.
     
  20. 05PreeUs

    05PreeUs Senior Member

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    I read somewhere on the PC list that a FLASHING light is caused by a misfire. As others have correctly pointed out, this is commonly plug, or coil induced, but excessive moisture in the sparkplug well was the cause in ours.