Couple months ago I brought my 1998 S70 to a good independent garage
that's specialized in European cars (esp. Volvo) due to persistant
Check Engine Light.

After being charged $70 for his diagnostic, I was told no code was
found. The light was simply reset and a new gas cap installed (they
found it leaky).

However, a couple weeks afterward the light came back. It actually went
off by itself once but after another couple hundred miles, it came
back. Also the light seemed to more often came up (after I reset it
with a OBDII reader) when the gas tank was near empty.

I'm afraid of being charged another $70 for nothing- at the garage or
dealer.

Anyone knows what's going on? My cheap OBDII reader can't read any code
either.

Appreciate any helps!

Ehien