Hi,
I'm new to this forum and a little stressed. I bought a 99 C280 just over a
week ago.  I love it, except the check engine light has been coming on ever
since I got it.  The dealer I got it from has put in an effort to see what's
wrong with it. At first we thought it was the gas cap (A common problem after
looking at all the threads online) after I learned to close it properly, it
came back on again.  The dealer had a MB mechanic look at it and he said it
was some sort of vacum leak, and tightened it.  It was fine for about an hour
then the light came back on again, so this time we got a whole new vacum
filter.  That seemed to fix it, for a whole 3-4 days the light stayed off and
I was just starting to relax and enjoy my purchase, when all of a sudden it
comes back on again!  I'm regretting buying this car, but I'm attached to the
luxury of it.  The dealer says it's probably just some sensor malfunction,
but that won't stop my anxiety until that thing is Off and STAYS OFF.  I seem
to have bad luck/judgement when buying a reliable used car.  I'm a bit jaded
and not feeling optimistic.  I wanted this car to be RELIABLE along with
luxurious.  My worst fear is being stalled in the busy L.A traffic that I
live, or it not starting when I need it to.  I'm a single mother with a small
toddler, so i'm a bit paranoid.  I'd like to know if this is a common problem
that is easily fixed (besides the gas cap thing) or is the MB mechanic
missing something.  I looked through the previous owners records and noticed
he had to have the transmission replaced early on, it now has 94k miles.  I'd
appreciate your comments. Thanks.