I have a 2001 S80 2.9..... The "Engine System Service Required" light with no apparent change in performance. It only comes on when the car is warm. I reset the computer and I get a code of "44" and "66". The dealer won't tell me what it means unless I bring it in an open my wallet. The only other thing I can add is the car has a small lull in power at cruising speed of 50mph. It is like "bounce" of the RPMs. I accelerate beyond that speed and it stops. Other than that the S80 runs awesome and smooth. I just had new tires installed....drives like a dream. Any diagnostic help would be appreciated!!

Thanks,
Brad

 

You need to read the codes through the ODBII plug.

 

Thanks for getting back to me....any idea about the RPM Lull. Ever heard of that???

Thanks!!!

 

It could be that the car goes into a "limp home" mode where it "protects itself" by not allowing you to accelerate above a certain point. Think of it as a governor of some kind. Only problem is, depending on how the car feels that day, it could be 50mph, 35mph, or even 15mph like I am experiencing recently in my car.

Unfortunately, you'll probably need to take it into a dealer to have the codes pulled and analyzed for you. While an OBDII code reader can be helpful, it doesn't necessarily pull all of the codes from the system.

 

Yes you need to have the codes read to see if that is causing the problem.