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Check engine light

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by desertprius, Jul 5, 2021.

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  1. desertprius

    desertprius Junior Member

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    2006 Silver Prius, 236,500 miles, new HV Battery, new 12v, new inverter coolant pump all at 231,000, drives like a champ. A month ago husband brought it in for oil change, for two weeks it smelled like something was burning. After that no smell. Then last week the Check Engine light came on, brought it in, shop called an hour later said most of the time it’s a gas cap. I assume there were no codes because they didn’t tell me of any. They got a new gas cap and sent us home. All was good for 4 days then CEL is back. Car still runs like a champ, no issues. Does NOT burn oil. No oil on garage floor. What is the next most likely thing to check? Note: 1) we live on a dirt road. 2) it needs to get emissions test in 10 days. 3) we do all the maintenance (except for cracked windshield, out here that’s not worth fixing). Thanks ahead. PS yes I looked at other threads. PPS If it was you what would you do re: emissions test?
     
    #1 desertprius, Jul 5, 2021
  2. SFO

    SFO Senior Member

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    Generally speaking, if there are warning lights displayed on the dash, there will be OBD2 codes (DTCs) stored in the ECUs.

    Knowing the OBD2 codes (DTCs), and any associated subcodes (INFs) can potentially assist in solving the problem in a timely fashion.

    Do you possess a Toyota hybrid compatible OBD2 scanner?
     
    #2 SFO, Jul 5, 2021
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  3. desertprius

    desertprius Junior Member

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    Sorry, no OBD2 scanner. Shop has one. But I don’t.
     
    #3 desertprius, Jul 5, 2021
    Last edited: Jul 5, 2021
  4. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    My first thought was that someone left the oil filler cap off after the oil change. And the shop is staying quiet.

    Is it the same shop every time? Have you guys looked under the hood yourselves? If oil fill cap was left off, you’d maybe be seeing a patina of oil all over engine bay, in particular the hood directly above.
     
    #4 Mendel Leisk, Jul 5, 2021
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  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Next thought: gross overfill at the oil change. This is terrifically common. Google the ramifications.

    For example: if excessive enough, the crankshaft starts dipping into the oil in sump, frothing it up, and then it won’t flow as well, and engine can overheat, gaskets/seals are more prone to fail.
     
    #5 Mendel Leisk, Jul 5, 2021
  6. Raytheeagle

    Raytheeagle Senior Member

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    Best investment if you do the maintenance yourself: an OBD2 scanner;).

    This way there is no guessing on the cause of the issue:).

    With a 15 year old car, the light could be in for myriads of reasons:whistle:.

    Having that tool for modern cars is the way to go(y).
     
    #6 Raytheeagle, Jul 5, 2021
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  7. mr_guy_mann

    mr_guy_mann Senior Member

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    There could be dozens and dozens of codes that can trigger the check engine light, with hundreds if not thousands of possible causes. Without at least having the codes all you know is that there is some kind of problem somewhere between the front and rear bumpers. If the shop said "a gas cap usually fixes it" then you might assume that there was a code for the evaporative emissions systems. But can't say much more at this point.

    Posted via the PriusChat mobile app.
     
    #7 mr_guy_mann, Jul 5, 2021
  8. desertprius

    desertprius Junior Member

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    I thought of oil possibly being overfilled. Had not thought of them leaving the filler cap offs, . I did look under the hood when I was smelling burning, thought maybe a hose but couldn’t see anything and radiator fluid was ok. Did not notice oil splatter. Yes same shop, they have never done that before, but there can always be a first time, will take a look inside the engine compartment today and check oil level. We don’t do our own maintenance, always take it to the pros. I like having a pretty good idea of what a problem might be before bringing it in, but it has been pretty trouble free despite recent work thus haven’t seen the need for an OBD2 scanner before.
     
    #8 desertprius, Jul 5, 2021
    Last edited: Jul 5, 2021
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  9. desertprius

    desertprius Junior Member

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    With other cars the check engine light has usually been an oxygen sensor, but didn’t know if that was common with these. Has been really trouble free for the most part. Don’t want the shop to say hey you need a new cat if we don’t. Has never had any oxygen sensors go out before. I always look at the cheapest items first hoping it is one of them, rather than the expensive ones. On a different thread someone suggested three way valve. Would codes tell you a difference between all of these?
     
    #9 desertprius, Jul 5, 2021
    Last edited: Jul 5, 2021
  10. ChapmanF

    ChapmanF Senior Member

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    Back to the last question in the first post, if it were me and an emissions test were due in 10 days, I would find a way to retrieve the trouble codes, in fewer than 10 days.
     
    #10 ChapmanF, Jul 5, 2021
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