Another TPMS question

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by cutter44, Mar 21, 2020.

  1. cutter44

    cutter44 Member

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    I did search the forums, but didn't see anything that I felt was similar to my situation.

    Since I bought my 2012 C4 (pre-owned), I have used the Hankook Optimo H426 tires for most of the year, then dedicated snow tires on steelies for the winter months. Every time I've done it, I've lived with the TPMS light on the dash while the winter tires are on, then when I put the Hankooks on, the light goes away and all's well. Well, a few weeks ago, I took off the snows, filled all four of the Hankooks up to 36psi as usual before putting them on the car, but the dang light hasn't gone out yet.

    So I figured I might try the reset procedure noted in the manual. Well, the steps don't match up with what I'm experiencing. As soon as I turn the car on (SmartKey) before I even go near the reset button, the TPMS light flashes for quite a while, then stops flashing and just stays on. I've tried holding in the reset button for several seconds, hitting it with the car ON and OFF, and nothing changes.

    I'm not really concerned, as I do check the tires regularly and they're inflated fine. And yes, I could just put a piece of tape over the light, which I used to when I had the snows on, but I'm just wondering why after several years of the same routine, now the light stays on all the time.

    Any thoughts? Thanks.
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Maybe one or more of the sensors has died?

    I'm on the same wavelength: I'd just ignore it, periodically check pressures. I don't fuss with tape on the light, just messes things up.

    At least until you're replacing that set of tires.
     
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  3. cutter44

    cutter44 Member

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    Jeez, you're fast, Mendel. :)

    Thanks for the quick reply. Any way of me knowing for sure without bringing it to a dealer?
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Techstream for sure, maybe some of the aftermarket gizmos too.

    There's a couple of experts here, who's user names escape me of course. Someone Tracy? And the New England guy?
     
  5. cutter44

    cutter44 Member

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    Okay, thanks. More importantly, other than the inconvenience of seeing that light (or covering it), nothing to be concerned about?
     
  6. Salamander_King

    Salamander_King Senior Member

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    Yap, as @Mendel Leisk said, flashing TPMS and staying on is the indication of faulty TPMS system, very likely dead sensor.

    Whatever you do, don't take your car to a dealer. Yes, they can fix it but will cost $$$. Most tire shops are equipped to diagnose and fix the problem for much less. If you know a friendly tire shop, they may even scan the sensor for free to let you know which one is not working. Or else you need to buy a TPMS tool that can scan and diagnose like Autel TS408 or better.
     
  7. cutter44

    cutter44 Member

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    Thanks. Or I can just ignore it and continue to keep an eye on my tire pressure, right?
     
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  8. Salamander_King

    Salamander_King Senior Member

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    Yap, just like you have been doing during winter, you just have to keep ignoring the light rest of the year.
     
  9. cutter44

    cutter44 Member

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    I can live with that. Or it might be time to break out the black electrical tape again. :)
    Thanks!
     
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  10. Salamander_King

    Salamander_King Senior Member

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    I don't know about C, but for my PRIME the TPMS light was way to the right side of the dash. I didn't have to do anything to ignore it. Totally out of sight.
     
  11. cutter44

    cutter44 Member

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    Yeah, mine is at the far right, but definitely easy to see. No more difficult to ignore than that airbag sensor light that stays on when no one is sitting in the passenger seat.
     
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  12. Salamander_King

    Salamander_King Senior Member

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    I use external TPMS sensors on my tires, so I don't have to check the tire pressure with a gauge. They are ugly, but far more functional than OEM TPMS in PRIUS that shows no information.

    IMG_20181115_105448-COLLAGE.jpg
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah, working yourself into a lather of this could be expensive. Inertia, not a bad guiding principal. (y)
     
  14. fuzzy1

    fuzzy1 Senior Member

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    If you don't have annual state inspections, and can reliably monitor tire pressures the old fashioned (before TPMS) way, then you have nothing to worry about, compared to the pre-TPMS era.

    But if you must pass an annual inspection, then this dead sensor will need to be replaced.
     
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  15. Salamander_King

    Salamander_King Senior Member

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    MA has inspection, but TPMS is not required to be functional to pass the inspection. Vermont, Rhode Island, West Virginia and Hawaii are the only four states that require functional TPMS. I believe Vermont was trying to change that law to remove the TPMS requirement.

    Screenshot 2020-03-21 at 10.02.39 PM.png
     
    #15 Salamander_King, Mar 21, 2020
    Last edited: Mar 21, 2020
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  16. fuzzy1

    fuzzy1 Senior Member

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    I've heard so many complaints on this over the years, that I was unaware that so many inspection states didn't actually require functioning TPMS.
     
  17. Salamander_King

    Salamander_King Senior Member

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    I too have heard from many people that warning light on the dash is automatic "fail" on inspection. Because of that false information, I believed I had to have functional TPMS to pass the inspection when I bought the first car with TPMS many years ago. Thinking I had to fix TPMS each time the sensor failed, I spent close to $800 on TPMS sensor replacement on that car at a dealer. I did not know then what a waste that was.

    The state inspection in many stations does not even follow the protocol very strictly. There are many stations that don't even know about the law. I've taken my old car to one station for inspection and it failed my car due to needing to replace the rusty brake line. But there was no leak. And the brake was fully functional. As it turned out, the law requires that the brake has to be functional but there is no clause about corrosion on the brake line. Any car driven in NE winter roads has some degree of surface rust on the brake line. Mine was no exception. I took the same car to the different inspection stations, and they passed my car no question asked.
     
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