I recently had a new 4.0L engine (jasper) dropped in my 2002 sport. Shortly after I got it back home on a cool morning start I got a check engine light. Shop had me bring it back in and it was code P0161. They replaced the sensor and since I couldn't get back to pick it up for a few days they had to jockey it around the lot until I could get there. One morning when moving it the check engine light comes on again, same code. They replace the sensor again and check that nothing is going to ground. Everything is ok. I pick up the jeep and use it a few days. Sunday morning I go to start it and the check engine light came one. Checked the codes and it P0161.
Any ideas? Could it be something simple like a gas cap? P0161 is circuit low voltage to bank 2 sensor 2. Not sure if it's just coincidental with the engine replacement or if something else is going on.