Check Engine while on Highway only

I have a 1995 GA with 3.1 V6 engine with 82000 miles. I do not drive many highway miles but when I do the check engine like come on the first time that I have to slow down. Once it is on, it stays on until I turn off the car. I am thinking it might be the O2 sensor. Any ideas????

on a computerized car it could be one of a hundred things. go to autozone and let the scan codes for u. they do it for free

I am having the similar, if not the same, problem. My check engine light seems to come on when I get the 1995 Pontiac Grand AM up to around 60 MPH and stays on until the car is shut off.

I've replaced the oxygen sensor and it continues. I've even taken up to O'Reillys and their computers did not find anything wrong. I've thought about dropping the oil pan, but being a VERY novice mechanic, I wasn't sure after reading the Chilton's book, if that was a task that I wanted to take on. This isn't one that you can just simply drop the oil pan and look at the oil pump. From the way the book reads, it sounds like it might cost me a pretty penny to have someone do for me.

Any help or suggestions would be really appreciated.

You need a TecII tool to scan it while on the road to know for sure. Dont rely on a cheap code reader , they cant trouble shoot. A quick diagnostic scan should only cost $30. Then you have optiions knowing exactly what the problem is.

It could even be a loose conection for the dummy light that gets a lil loose when the air is moving faster through the engine.

I would bet that one of your oxygen sensors is bad, you may have one, you may have two depending whether or not your car is OBDI or OBDII.