I have searched the forums but can't seem to find much info on the cap that covers my OBD port!
I have an E46 330d 2001 and after owning it since September have never had the plug in place' it was in the glove box and I only realized what is was for yesterday!!!
Anyway, I put it back in its rightful place and when I drove it today noticed the car runs so much better!! It seems smoother, pulls like a train and is so much more responsive!
Should this have made a big difference?