That's a ridiculous price for diagnosis, but not unheard of to be broken. My brother had a F150, that the air went out at less than 1 year old. The dealer told him they couldn't service it at all, because that was when they first changed to the 1234YZ, (or whatever it is, I can never remember). They didn't have equipment yet, and said it was too expensive to buy. He had to find another dealer. His air went out 3 more times, and the last time it was out of warranty and cost him over $1,000 . He got rid of it and bought a Ram.