2005 XC90 Trans issue.

see if the fluid is burnt , it may not even have a dip stick , see if there's a plug of some kind remove it and stick your finger in there and you should come back with some fluid . If the fluid is nice and pink then the tranny may be worn , any performance car gets beat on , we use to call them disco cars .

The 4T65 transmission in your XC90 T6 is notorious for valve body failures, and that sounds like what you're experiencing. The first thing to do would be check the fluid, if there isn't an issue with the fluid level/quality, it may be time for a valve body.

Thanks for the input. Yes, it has a dipstick, the fluid doesn't look great, as that was the first thing I checked. I did have to add a quart about a month ago. I've found out recently about the notoriety of these transmissions. The odd thing is that when it acts up I will shut it off for a few seconds and restart it, then it acts relatively normal for a while, sometimes hours, other times just a few minutes, that's what has me stumped, I've never seen a transmission act like it's gone then act normal after shutting it off for just a few seconds, that's why I was questioning whether it may just be an electrical issue with one of the solenoids or something. It's in the shop now so I'll have an answer by the end of the day.

Yup, the AW55 transmissions are similar. It's something to do with the electronic side of things, they can "reset" but the problem soon reappears.