[absentminded]

I had the same problem that many of you mentioned about getting an error message despite having the proper code for my Acura TL. I even went to the dealer prior to reading this post to learn that the dealer did not have a good explanation except you need to bring it in when the service department is open. After I got home I started to do a bit research and ran across this post which got me to thinking and helped me find a quicker solution which I am hoping will help others that read this.

Take your car into a parking garage underground where you will not be able to get an antenna signal, thus the antenna signal cannot interfere with the input of the radio code. I took the car into an underground garage that is two stories under where I know from past that the car antenna did not pick up anything. I entered the code and to my surprise it worked. No need to open up the side panel and disconnect the radio.

I hope that this might work for someone else.

Absentminded.