I just recently went through this. I had the harness inspected at every service visit. It wasn't until I pulled the plastic engine cover and air box off and looked myself was it noted. I could see it plainly on the wires as they came out of the sheathing to go to the connectors on the temp sensors at the front of the engine and onto the fuel injectors.
Now, here's the kicker. I had the "wiring harness" replaced, then the check engine light came on. It went back into the dealer, and that's when they found that the lower harness was also bad. I didn't until then know that there was more than 1. It turns out that the lower one is MUCH more expensive and more time to replace. To the dealer's credit, they did it all, and didn't charge me a thing. (They billed 14 hours! of warranty labor on the invoice for the lower harness!!!!).
Moral of the story, ask them to inspect both upper and lower harnesses, carefully, then do it yourself.
(Oh man, this car is sooooo fast.)