I am a little confused ok a lot!!! I am thinking on replacing the front o2 sensor, ok they have so many types most are splice in, my book tells me there is a difference from the upstream and downstream, the one the sell aftermarket don't, plus some are 4 wire and others a 1 wire, I want to replace the front upsteam I think it is a 3 wire. what do I do ? other then buy it from Kia which wants a few fingers for it, I have a 2001.