Transmission

Transmission problems are rare in these cars. Did the prior owner change the fluid and put in aftermarket ATF? As a cheap fix, you could drain and refill the CVT with Toyota brand fluid. If that doesn't fix it, I would sell the car. There is a video on how to change the transmission fluid in the maintenance part of this forum. It is fairly easy to do it yourself.

You might also want to get another opinion. Wheel bearings can also make noises from the front and that may be more likely.

 

As the transmission is not a weak point of Prius, you may buy a used one, should be much cheaper than a new one from Toyota.

 

A bit of a "whining" noise is normal on a Prius just from the power electronics, which do switching at a frequency you can hear (and that varies with speed).

As you haven't had the car very long, have you compared it to anybody else's Gen 3 Prius just to make sure what you're hearing is out of the ordinary?

I'd hate to see all the bother of a transmission replacement just because a dealer saw an opportunity to respond to your question by selling you one.

 

I would get a second opinion from another prius owner.

The sound possibly may just be the regen from braking and electric from accelerating ?

 

I would think it is a wheel bearing before I would suspect the transmission. There is no slip in the transmission as it is a constant mesh gear. There are no brake bands like in conventional automatic transmissions.

 

Already stated above, but as a relatively cheap and not too difficult exercise to see if there's any change to the noise you're hearing, I'd change out the trans fluid.

The previous owner(s) likely didn't do it as this is a common thing not to do on the 3rd gen and if the noise isn't from the trans, you're only going to do yourself a favor swapping out fluid with 120K on it.

I did mine in my car port, used four jack stands to get the car almost level and it did a gravity fill from the top of the car using a funnel and thin hose. I used four quarts of Red Line D6, imo, it's a superior synthetic to the Toyota WS fluid, but it's perfectly fine to use the WS too. Some member here has changed his trans fluid multiple times now using Valvoline Maxlife ATF. which would be the most cost effective of the three. He claims he's had zero issues with it. Your car though, so your choice.

 

Low on transmission fluid?

Pixel XL ?