How to check error codes

What shape is your OBD port? If it is a rectangle, then there is a trick that I can detail for you. Check out this guide: https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

If it is a trapezoid shaped connector, then you likely have the rare OBD1.5 setup, which is where your computer speaks the OBD1 language, but has the OBD2 port. Unfortunately, since it is rare, you have to find someone with the right scanner and the right adapter. If you find a mechanic that has been doing this for about twenty years, they will probably have the right scanner. See the image below for roughly what the port would look like.

1995 Corsica will be the transition OBD port. None of the chain shops will likely have the correct scan tool. You need an older tool that can read both OBD I and OBD II. The Snap-ON MT2500 is one that will work, as will the OTC Genisys (not the Touch). In both cases you need the software that covers the vehicle you have. There are others out there like the Tech 2 with the adapter cable but the Snap on or Genisys are reasonable on eBay.

Snap On machine like this - ebay # 312165807760
Genisys machine like this - ebay # 263616906548 or 223001698803

Personally I like the Genisys unit a bit better as it does more without cartridges.
You can also buy the newer EVO unit as long as it comes with the older cables as well.

Most of the higher end newer tools can connect as well but they need a powered adapter and the software. Because the 1.5 is getting rare they only buy the newer software.