[wjones14]

OP, first thing, sorry for your troubles, and hope everything is fixed successfully.

The 2.5 hours is definitely a red flag, assuming all he did was to change the oil and rear diff fluid.

But not sure how the rear diff pinion seal could have anything to do with the noises and CEL? When that seal starts leaking, you lose diff fluid obviously, but you shouldn't get any noises until the fluid is gone or almost gone. I'm not sure about how different the 1LE eLSD is from other rear diffs, but a leaking rear diff pinion seal is something that is typically repairable by just replacing the seal itself. I've never heard of the diff needing to be replaced, unless it ran for a long time with little or no fluid.

The other thing is I'm not sure how the tech could have screwed something up while changing the rear diff fluid, where the pinion seal would start leaking? The only thing I can think of is that he used the wrong fluid.

Since the car was trouble-free for 3000 miles, and you first noticed a noise the day after the service, prior to putting the car on the track, it's reasonable to assume the tech screwed it up somehow.

For those of us who don't know, is FL2K a drag strip?