I've got a '93 Lumina Euro (car) with the 3.1 engine. For and old beater, it's in pretty good shape. 125k on the odo. I take very good care of it. Oil change every 2,500, etc.

Once a week I drive about 35 - 40 miles to visit some friends of mine. I've noticed my Service Engine Soon light comes on after about 5 - 10 miles after I get on the highway. Sometimes it goes off, but most of the time it stays on the whole trip.

I drive the car all over town all week long with no light. Only on the highway. It never acts "funny", doesn't got hot, no other lights come on.

It does have a small oil leak, but not excessive.

Really can't afford a new car right now, that's why I baby old "Gertie" as much as I can.

Is this a serious thing, something that needs to be looked at? Or can I slide?

Dealer wants 40 - 70 bucks just to diagnose. Any help anyone can give would really be appreciated!

For the record: Owned the old car for almost 3 years now, shocked me how good it's been. Made me believe in Chevy's.

 

Hi Tony B23,

Welcome to the Chevy forums.

Sounds like possibly you have a bad gas cap, and the only time you drive it enough for it to show up as a problem is when you take your long ride.

Try this:
When the light comes on, drive the car for another 10 miles or so. Then park, leave the engine running, and get out and loosen the gas cap. Do you hear a suction? If so, your gas cap needs to be replaced.

Also, look around on the engine for any bad vacuum hoses or leaks. Wait till the problem lights up, then find a quiet place to pull over; with the engine running, pop the hood, and see if you can hear any hissing noise.

 

You should go to Autozone the next time the light is on and have them scan it (it is a free service), then report back with the code. It can come on for many reasons without the code there is no way to know. I could give you a ton of guesses but without a code they are worth nothing.