Transmission fill plug

Discussion in 'Gen 5 Prius Main Forum' started by Shawn Shawn, Feb 2, 2026 at 12:58 PM.

  1. Shawn Shawn

    Shawn Shawn New Member

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    Hi everyone — quick question: can someone confirm where the transmission fill plug is located and, if possible, share a photo of it?


    I’m trying to verify whether the plug I’m looking at is the transmission fluid fill plug (or if it’s actually a fuel plug / something else). Thanks!
     

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  2. Mendel Leisk

    Mendel Leisk MMX GEN III

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    From reading through attached, looks like fill and drain bolts for the transaxle are socket head cap screw style (female), with recess for 10 mm hex driver. Info:
     

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  3. BiomedO1

    BiomedO1 Senior Member

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    Nice bolt head - how about a zoom out picture so we can get an idea of the location of that bolt?
    FWIW; the fill plug is next the output CV shaft.
     
    #3 BiomedO1, Feb 4, 2026 at 9:58 PM
    Last edited: Feb 5, 2026 at 12:57 AM
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  4. Georgina Rudkus

    Georgina Rudkus Senior Member

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    TE means that the transaxle uses TE fluid.

    Evidently, the drain plug was upgraded on the OP's vehicle to make sure that the technician knows that the transaxle uses TE fluid and not the previously used WS fluid in earlier models.
     
    #4 Georgina Rudkus, Feb 4, 2026 at 10:01 PM
    Last edited: Feb 5, 2026 at 12:57 AM
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  5. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Here’s a screen grab from my previous attachment, showing fill and drain bolt locations. No mention, but the views are apparently different, so seems like the two bolts are not on the same face.

    IMG_3185.jpeg

    typical terse/cryptic Toyota repair manual style btw. :rolleyes:
     
    #5 Mendel Leisk, Feb 5, 2026 at 10:09 AM
    Last edited: Feb 5, 2026 at 11:11 AM
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  6. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Sorry for the confusion.

    I meant fill plug. The drain plug is the one with the 10mm hex socket.

    The plug marked TE is apparently the fill plug.

    Both, however, are still an M18x1.5 thread pitch.

    If it was my car, I would replace t h e drain plug with a widely available M18x1.5 aluminum magnetic drain plug.
     
  7. Gokhan

    Gokhan Senior Member

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    If it is on the transmission, it is not a fuel plug.

    Are you at 60,000 miles already?
     
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  8. Georgina Rudkus

    Georgina Rudkus Senior Member

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    The fill plug, marked TE, removes with a 24mm socket.
     
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  9. Gokhan

    Gokhan Senior Member

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    It is certainly not 10 mm according to the OP’s photo. It looks like they have changed the design.
     
  10. Mendel Leisk

    Mendel Leisk MMX GEN III

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    I’m genuinely curious how you found that out Georgina; did you have access to one?
     
  11. Georgina Rudkus

    Georgina Rudkus Senior Member

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    The TE marking is the giveaway, since TE fluid is the current standard for the Gen 5 transaxle.

    I conject that Toyota had an issue of service technicians assuming that Gen 5 transaxles were an extrapolation of the WS standard used in most all Toyotas over the past 20 years. Probably due to continuing mistakes with Gen 5 transaxles being filled with WS, Toyota decided to issue the TE marked fill plug.

    When Toyota went to CVT transaxles, they began to mark the transaxle fill plugs with FE to insure that the servicing technician is not to use WS.

    Technicians noted in many many videos in CVT service on Toyotas with an FE marked fill plug used a 24mm hex socket.

    That being, it would almost assured that the 24mm socket would be the standard on the TE fill plug.
     
    #11 Georgina Rudkus, Feb 6, 2026 at 8:22 AM
    Last edited: Feb 6, 2026 at 10:32 AM
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  12. Gokhan

    Gokhan Senior Member

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    Come on, it is obvious from the photo. It is an M18 thread. Then, how can that hex head be 10 mm? Previously, the bolt head was much smaller than the bolt flange, which is why. Moreover, how do you expect to fill oil through a hole about 6 mm wide if that head was 10 mm? Apparently, they enlarged the bolt head now so they could write “TE” on it.
     
  13. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Toyota chose a 24mm head for the reason that most all standard socket sets do not include this size. Practically, it could have been 19mm as the heads on the M18x1.5 magnetic aluminum drain plugs that I replaced the 10mm OEM plugs on my Gen 3 transaxle.

    If you look on the head of hex bolts, the TE marking could have been easily placed on bolts with hex heads as small as 8mm.
     
    #13 Georgina Rudkus, Feb 6, 2026 at 4:31 PM
    Last edited: Feb 6, 2026 at 5:10 PM
  14. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Seems most appropriate on the fill plug though.
     
  15. Georgina Rudkus

    Georgina Rudkus Senior Member

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    They probably chole 24mm and 10mm socket hex, since the casual DIY car owner will not usually have these sizes in their tool sets.

    These sizes would only be acquired by serious DIY persons who Toyota hopes will likely know what they are doing.
     
  16. Gokhan

    Gokhan Senior Member

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    The oil drain plug socket was 14 mm? It’s been a long time since I did DIY oil changes.
     
  17. Gokhan

    Gokhan Senior Member

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    Really? How can you work on a car without a full socket set—casual or serious?
     
  18. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Really! How many standard full socket sets have 24mm sockets or 10mm Allen wrenches?

    I've seen videos of those vehicles with 17mm hex drain plugs on both their engine and transmission oil pans, where the transmission was drained and the engine oil double filled.

    This was done at one of those quick oil change places.

    https://youtube.com/shorts/uzhUt7jfYPc?si=hI-_fa1mBWLQiuEN
     
    #18 Georgina Rudkus, Feb 6, 2026 at 4:46 PM
    Last edited: Feb 6, 2026 at 5:21 PM
  19. Gokhan

    Gokhan Senior Member

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    My Gearhead brand 1/2” socket set goes up to 24 mm. But I guess I am more of a serious DIY type.

    I thought the previous one had a 10-mm bolt head, not a hex hole.

    In any case, anyone undertaking an ATF change or similar work must be prepared to make a trip to the auto parts store to obtain any missing tools.