Service engine light

Hi. I am new to this site and I must say the problems really scare me! I just purchased a 2002 Passat 1.8 Turbo 77,000 mi. When we drove test drove the car, the service engine light was on, the dealer (not a volkswagen dealer, I might ad) told us that this came on because they sprayed the engine, and that VW are very sensitive cars, for us to bring it back and they would correct the code. Brought it back, they gave me a rental, they called me back and said they couldn't pull the code they had to send it out to the VW dealer. Next day they called and said it was ready. Upon pick up they said the dealer didn't find anything wrong and got the light out. Never saying on the paperwork what code was coming up, but it read as if someone had changed the battery. IS THIS TRUE? WILL THIS MAKE THE CHECK ENGINE LIGHT APPEAR? Drove back to work and before I got to work, guess what the light was back on they told me to bring it back in on Monday.

I also notice that there is hardly any power on initial take off and it feels like from first to second like I have a manual shift instead of automatic, is this normal? As you can tell this is my first VW.

Thanks for any help I can get.

Take it to a larger auto parts chain like Autozone who usually will read the codes for free. Compare them to what the dealer is telling you.