antifungal

Hey all, long time no posts here! Feels good to be back. I recently got a tune up on my 06z. I changed the belts, then changed the spark plugs. However after doing so, the CEL came on. It turned out i needed a new o2 sensor. Changed that and the CEL light came on again.. I checked the code just now and I believe its reading 2103.

I did a quick google search and couldnt find anything really related to that code. Has this problem happened to anyone else? My next guess and I pray Im wrong is that its the cat converters..

Funny how a $500 tuneup is turning into 1k :/