Camshaft regulator or sensor?
 

I have a 2002 S80 with a 121000 miles on it. On Friday I had the 120k tune up and had a brake hydraulic cylinder (?) replaced (I had hissing noises coming from the brake pedal). The next day my Check Engine light came on (1st time ever), though it seemed to be operating well. I took the car back again today and was told that "Coincidentally" my camshaft regulator needed to be replaced. My question is - Is it possible that this is a coincidence? Or am I being conned by the dealership that has always fixed my car? I'm a bit perturbed over the additional cost since I paid over $2k only last Friday.

Coincidentally stuff like that happens. Not all the time, but it does. Hopefully that is the case with your S80