Ok I bought a 95 neon on Thursday, 65k miles clean, etc. but today my CE light came on, I got the codes and what I got is

12: Direct battery input to PCM was disconnected within the last 50 key-on cycles (I have no idea what this means, or what I can do to fix it)

and I got

21: 02s sensor problem (oxygen sensor), upstream or down stream (I figure this means I have to replace the 02 sensor, which shouldn't cost much)

anyone who can help me understand or fix it will be my hero forever :D

Code 12: harmless. This basically means that the battery was disconnected at some point in the car's last 50 key cycles. Since my fiance and I have done lots of stereo work to my car (which requires disconnecting the battery at times) I always get this code. It's just an FYI.

EDIT: this code will not cause your CE light to go on. You will see this code only when you do the diagnostic check.


Code 21: You need to take it to the shop so they can figure out which O2 sensor it is. This is something that needs to be done, but it's not an emergency. Your fuel economy might suck until you get this done. 65,000 mi. sounds about right for it to go out if it is the original one. It is a wear n tear item that will have to be replaced every so many miles.

EDIT: This code WILL cause your CE light to go on, hence the reason the Code 12 happened to show up also.

If that's the only problems you are having for a 95 Neon, you are doing pretty good :)


On a side note: When you bought the car, did you get any maintainence records for it? Has the timing belt been changed yet? If not, I would suggest doing it soon. The manual says you can go 105,000 miles before needing to do this. I would not let it go that long. Every other car I had required the belt to be changed at 60,000. I would also highly suggest you spend the extra $100 and get a new water pump too if you end up changing the belt. The timing belt is run off the water pump. On my 97 Neon, I had changed the belt at 65,000, but at 96,000 my water pump seized, then my timing belt shredded, and that cost me a new motor. Not trying to scare you or busrt your bubble..just don't wanna see another Neon owner go thru what I did.










So.....am I your hero? :D