Service Engine Soon

Why is the service engine soon keep reappearing and I just had a tune up? Just recently got the car though. I have no book manual so I am sorted lost for repairs.

bad O2 sensor

http://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

This link will tell you about SES light and how to read codes. My guess is error 32, usually caused by a vacuum leak, which will be hard to locate.

During a routine tuneup, sometimes wires get bumped and old, brittle connectors are jarred loose, check to make sure everything is plugged in tightly where it belongs - a vacuum leak, as mentioned above, can be caused the same way - old hoses get bumped and start to leak. Check the codes before you just jump in and start replacing things. (If they are stored - a random flash of the check engine light might not set any)
To get at the ALDL connector to read the codes, remove the trim panel that the cigarette lighter is attached to (2 screws)
Many auto parts stores, including AutoZone, will plug a scanner into this connector and read the codes for you free of charge.

Hint: Trouble codes that refer to a particular sensor or control are NOT a sure fire indicator that the part is bad, the problem is often in the wiring to the component.
Hint: If it only comes on when the car is warm, the O2 sensor is usually to blame.
Hint: False trouble codes such as IAC motor codes can be caused by a vacuum leak - the #1 sign of a vacuum leak is a higher then normal idle (most 4 cyl Fieros idle @ 800 rpm once warmed up for a few minutes)

Well,
I appreciate all the love you guys.. But it's not the o2 sensor. It must be the egr valve that has a leak. That's the last thing I am going to change out. Everything else is new. The pipe looks a little old and rusty. Plus AutoZOne won't do the diagnois unless its 96 and up. I think I am going to open up a place for the 95 and older only. Since people just hate to fool with older cars. Thanks for everything.

They must have a scanner for OBD Generation II cars only.
Oh well, you can check the codes yourself just by grounding the diagnostic terminal with a paperclip. I don't think a leak in the manifold to EGR pipe would set a code, just make the exhaust noisy. Might wanna check the codes before making any guess... it gets pretty expensive.

Go to Autozone, they give you the little steel clip to trip the codes, the reader is under the console, tell them the code and they give you a print out of what it maybe.