Try putting an automatic p28 on a car that has a manual transaxle... A CEL is the least of your problems. The engine won't rev past 4k. It does matter. Make sure you get a p28 from a manual civic.
LMFAO! BOOYAH! That is SOOOOO TRUE! And forgive me man, but I can't remember your name for the life of me, LS. Was it David or Michael? haha Sorry about that.
Anywho, this happened to me yesterday! haha! I had been waiting for around two months (yes, I have a lot of patience) to have my mechanic install my chipped P28. Well, when he installed it, he took it for a ride with another guy and all I heard was it getting stuck, as they went down the street. They came back, looked at me and started to talk. I raised my finger and asked "Did it get stuck at 4,000 rpm?" They both looked at me as if I had been in the car with them. haha It was GREAT! Then they asked how I knew. I told them that I have sonic ears and could hear them going down the road...that and I actually read about that problem on here and that my guess was that it's an automic P28. They laughed, then the guy I bought the P28 from showed up with a different chip. I let him try it, even though I figured I had been given the wrong ECU. Case and point, my ECU is being changed out for a manual and will be back to me tomorrow. The guy thought I was going to be mad and I just laughed. Anywho, that's my story and I'm sticking to it.
On a side note, the guy that came over took his chipped P28 which had the same program burnt on it, took it for a ride and said my car screamed. Now THAT really made me smile. haha
The moral of the story is, get the right freakin' ECU the first time.