vtec not working on b18c swap

jdm b18c swapped into a 92 civic cx. I use to have this swap in another 92 cx and the whole thing was working fine. I had a mechanic do the first swap and this time I did it myself. I have read that 92 civic have already vtec wires and all I have to add is the knock sensor. Anyways, Im getting two engine codes 23 (knock sensor, no surprise there) and 41 (Primary Oxygen Sensor) I dont know what that last one means. Ive heard of stories that you fix one code and the other is gone or it is something more serious and this is what is messing up my vtec. can anyone help, please!!
thanks in advance, Leo