The transmission sometimes it automatically shifts gears?

2006 TOYOTA YARIS
175,000 MILES • 1.2L • 2WD • AUTOMATIC
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Hi, my car seems to be having a transmission, maybe a gear selector problem. Sometimes it automatically changes gears okay, but other times it randomly stops at gear then after a few hours or day it's back to changing gears normally. The transmission fluid is okay.
Mar 18, 2025 at 9:49 PM
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When the transmission does not shift does the speedometer work? If not, I would replace the VSS sensor. Also, do the gear selector lights come on in the correct location, in other words when you are in drive does the gear selector lights come on in drive? We should run the codes in case there are cods stored, this guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is the location of the VSS (speedometer sensor) so you can swap it out which is the most common cause of this kind of problem, (if the speedo stops working at the same time). I have seen the input shaft sensor cause this as well but there should be a code for it. Check out the images (below). Let us know how it goes.
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Mar 19, 2025 at 11:35 AM