hey all,
last week i took in my 99 grand 4.0L due to a loud muffler. they replaced just before the muffler all the way to the tail pipe. next day get check engine light on. autozone code read said PO138. (circuit condition heated oxygen sensor bank sensor 2) listed causes as: 1. oxygen sensor defective 2. fuel system running very rich or lean (check other codes first) - by the way no other codes 3. engine misfire - but have no strange noises 4. fuel pressure very high or low fuel pump or pressure regulator. I looked under the Jeep and saw that on O2 sensor socket was part of the new welded pieces. i find it very coincidental that i had this done and this code is now being registered 10 hrs. later. gonna call the muffler dude, but i wanted to see what you guys think also. seems like they may have messed it up. any help is appreciated.

 

did they put a new o2 sensor as well?

 

so i took it in and they thought the O2 sensor may not of been put in far enought into the pipe then they saw another small exaust leak that they fixed, the check engine light went off. about 20 min later they said, went back on. they said the catalytic converter may be going bad and causing false emission readings on the sensor. when i picked it up it had no "*****" in it with pickup and would not shift to passing gear when getting on it. pulled over, restarted the jeep and all systems look good. i can put up with the check engine light on, but just want to make sure nothing else is afoot.. any suggestions or insights??

 

I had a no power issue like that once with a Sunbird. The catalytic converter was clogged and needed replaced. Did that and it ran like a champ the rest of the days I owned her.