C
Craig M
Guest
on my 97 jeep grand cherokee 4.0 my computer keeps spiting out the code 21 and 12 now i know what the codes mean and i know that 21 is my o2 sensor but it sayes up stream and the thing that confuses me is is that the one in the cat or on the manifold so that's part one part two is the code 12 now this is power to my pcm was dissconected with in the last 50 starts and basicly it is telling the computer that i have tried to erase a code by disconnecting the batterie witch i did about 4 years ago and not sense now how do i get that code off of my computer so that i can have my truck inspected now this code has been on my truck fro about 4 years please help thank you