I just bought my 99 s80 in January. I love the car but it has a random problem. When driving on the interstate randomly the car will turn off the cruise control and lose all power. I have to pull over, turn off the car, wait a few minutes then it would start and run fine. Therewere no messages or check engine lights. I took it to the Volvo dealership, there were no codes saved and they didn't have a clue what could have caused it. This happened two more time exactly as before. Now starting about 3 months ago it would happen but now the car won't start at all, I had to have it towed. First time it wouldn't startI had ittowed to the Volvo Dealership, they replaced the antenna loop, they said the computer probably couldn't read the key. it seemed to run fine until about two weeks ago when it happened again. This time it happened so close to home I just towed it home. The next day it started fine so I'm assuming that this is a computer problem and it resets after a certain amount of time. I drove it to the dealership the next day, they replaced the antenna loop again. Exactly one week later same problem, had it towed home again and it started the next day. It's now at the dealership and I told them I don't want the car back until it's fixed. They are driving it about 80 miles a day (I drive 120 miles a day commute) but there is no telling when it will act up again as it is completely random. I should mention that the 3 times that it's had this problem and wouldn't start again when I try to start the car after it's died it quickly displays a message that says something like check start inhibbitor. I'm sure this message is why they keep replacing the antenna loop but I'm starting to think it has nothing to do with that. Has anyone else seen any problem like this or know of a quick way to get it to act up? The dealership said they can't do anything without it acting up or displaying a message or a code. At the rate they are going I'm going to have a 1000 dollar fuel bill along with the repair.

 

Sounds like the car immobilizer (theft prevention) is malfunctioning to me.

 

They have replaced it twice, I was wondering if it could be related to the TB problems, it seems some symptoms are the same.

 

The immobilizer only works for starting the car. Once the car is running then it doesn't work anymore.
I am wondering it the fuel pump is causing the stalling problems.

 

Why would the car not start up again until 8 - 12 hours later? I tried starting it up right away, and even 3 hours after it happened but wouldn't start. Then the next day I had no problems ran perfectly until the next episode. Also, if the reason it won't start up is the imobilizer, is there a way to either bypass it or reset it?

 

No way to bypass. Have you tried a different key?

 

Yes I have 2 keys and neither key will start the car when this happens.

 

I started running into another problem today when it won't start do you have shift indicator light?(Orange one)

 

Well the car was at the dealership for 2 and a half weeks. They cleaned the TB and said they "hope" it's fixed. I think it's time to sell.