code solutions?

[Trailer Ray]

So I'm getting the xj ready for its second emissions test. I replaced the o2 sensor which took care of the cel, now its throwing a misfire cylinder 3 code and a random misfire code. Do you think that's just cap rotor wires plugs? I'm going to start there I just figured I'd see if anyone knew of anything that might throw those. Its also throwing a manufacturer transmission code? I bypassed the nss is that why or could that just be low fluid or a dirty filter or do I have something to worry about? I wouldn't be terribly worried about the misfire codes but I heard they could fail me again for those. Thanks for any replies/ info.

[H8PVMT]

you could check your vacuum lines, at least that's what my research on a 0300 code lead to.....still haven't fixed it yet. You could always pull the battery cables and then drive 200 miles and get it inspected before the light goes back on, that's what I did.

[Trailer Ray]

OK so after a little while my heck engine light is back on. Would misfires throw it on? I'm going to see what codes it shows after work today but I'm just curious if that's what caused it to come back on?

[H8PVMT]

that's what mine does, it goes on and off throwing a 0300 random misfire code

[Trailer Ray]

Hmmm... I'm going to be checking into it more this weekend.

[Trailer Ray]

bump. i replaced the 02 sensors and plugs, wires, cap, rotor, and ignition coil. i have no codes for the o2 and misfires anymore. however, i still have the po700? i believe thats the number, its the code for a manufacturer control transmission. im not sure what it means but its making my cel stay on and im wondering what it means. the tranny isnt slipping or anything and it seems fine shifting and whatnot. i bypassed my nss and never re wired it back to normal, could this be the cause? if anyone has suggestions as to what it could be that is causing this tranny code to come on it would be greatly appreciated. i dont have much longer before my rejection sticker is up. thanks.

[Trailer Ray]

Update. So I've done some searching on the po700 code and I didn't come up with a lot. The main cause from what I found was the tcm. Would this be a good bet on what's causing the code and cel to come on? Also after I change it do I have to go to the dealership and have them reset the code or something. Also how easy/ hard is it to change? I know its been discussed on here but its tough to search threads on my phone. Thanks.

[Trailer Ray]

yaaayyyyyyyy

update: no more check engine light and codes. the po700 turned out to be a neutral safety switch being bypassed. since all it showed on the obd2 at autozone was a general problem with the tranny, i went to aamco to get a more detailed free reading. it came up with a problem with the neutral safety switch. when i first got the jeep i was troubleshooting some starting issues and i forgot to reconnect it after i had solved all the issues i was having. hooked it back up and voilah (is that how you spell it?? haha) no moar cel for teh win