I have a 2003 S-Type V6. I have noticed when I first start driving before the car is fully warmed up, there seems to be a slight noise briefly when going up slight inclines (sort of like going over a tractor treads in the road). It only does this a time or two then is doesn't repeat. I am thinking maybe transmission or rear end, but I am no mechanic - thought maybe someone in here might have an idea or suggestion what this might possibly be. Thanks.

 

definetly don't drive till car warms up, you can pop codes and trigger faults.
I have found patients does help.

 

Good advise oldiebutgoodie on a 12 year old thread. There have been many advancements that are proven since the original post.