1995 Buick Riviera CHK ENG Light

Bought a 95 Buick Riviera from a small dealer in North Carolina. This car
came from Virginia and the CarFax said it
passed an emission test every year until its last check in Oct 2006 at
42,000 miles. It now has 45,000 and the test
drive went well. On the drive home the check engine light came on with no
performance loss or rough idle or rotten egg
smell from the exhaust. When you shut it off the check light does not come
on. Sometimes will come on after a few miles
and other times I have gone 40 miles and it never came on.

I went to 2 AutoZone stores to let them scan for a code but at both places
an elderly person was using the scanner and
both places could not get the scanner to communicate through the aldl
connector. (I suspect they needed a different
connector)

I went to another shop and I don't know how the fella said got a code about
the EGR valve. They said $60 to clean the ERG valve.
Seems to me if it were and ERG problem the light would be on right away.
I talked to the original owner and although it has a supercharged engine he
never ran anything but regular unleaded
gas. Would you go with the ERG cleaning for $60 or try something else?

n8nyu@yahoo.com