I changed my ATF about a month ago and afterwards, noticed an ATF smell in the cabin when I had the outside air on. It's only when the car is stopped. It's not overbearing, but definitely noticeable. I've kept track of the ATF level and I'm definitely not consuming or leaking any. The level is exactly the same it was a month ago. Nothing has changed with the way the car or transmission runs either. Runs as good as ever. The weird thing is I can't seem to track down the smell in the engine bay. Even when smelling way down by the transmission itself, with the car on or off, in gear or in park - no smell. Just smells like "motor". I spilled a little when refilling but I've probably spilled a bit every time I've changed it and never noticed any smell with any of those past changes. Also, it's been a month so I figure it would have dissipated by now. Oh, and I've pressure washed the engine bay twice with engine cleaner detergent and hot water and still have the problem. I know that's a little frowned upon but it didn't cause any problem. And it pretty much looks new now. No oil, dirt or dust at all. But unfortunately it didn't help. The smell is still there.

It seemed to have started at about the same time I changed the front engine mount, which required unbolting some of the ATF cooler lines from the mount. But there was no need to break any seals on the lines (e.g. no fluid was actually spilled or collected - just the lines moved aside to get the old mount out and the new mount in).

I've mitigated the smell by setting the air to recirculate, then cracking a window or the sunroof so the air doesn't get stale. That works fine, and pretty much eliminates the smell. But it's not really ideal.

I've heard there's some sort of ATF "vent"? If so, would that potentially be the source? And why now when it's never done it before?

Has anyone else had this problem?

 

did you get some on your carpet/mats via your shoes?

I'd also check coolant levels just to be on the safe side. Sometimes motor smell can be heat! Or if you've used any engine bay dressing it could be the smell of that .

 

You didn't tell us what year TL you have. The 2009-2011 & 2012-2014 have different transmissions.
Nevertheless, transmissions have vents but that's just to allow small amounts of air to escape from the thermal expansion and contraction of the fluid and air in the transmission.
Otherwise internal pressure would build up.
The vent is on top so fluid should never escape unless you car turns on its side or upside down.

If you spilled some during refill it's possible that some fell upon the exhaust.
This certainly would explain your situation if this were the case.

 

I have a 2012. I've considered both of those possibilities but I don't think that's where it's coming from. Since the smell is only there when I'm stopped, I don't think it would be the mat or carpet. But I'll check it out to make sure. And I know I spilled a bit but it's been a while. I'd think it would have burnt off by now. Kind of like oil. I sometimes get a bit on the exhaust but the smell is gone after a day or two once it burns off.

I'll have to search for the vent and see if any excessive smell is coming out. Does anyone know approximately where the vent is?