I have a 2007 JK that I added an AFE header and exhaust system to. After about 6 months of driving it with no issues I got a P013C O2 Sensor Slow Response rich to lean on Bank 2 Sensor 2. It seemed to reset itself for about 3 months as the check eng light would come on and off for various lengths of time. Then it went solid on. Since it was such a while since I made the change I figured I needed to replace the O2 sensor which I did. The error code came back almost immediately again periodically going on and off for various lengths of time. I took it to a jeep dealer (I never do that, no trust) they put on another o2 sensor, same result, they swapped with one that was working, same result. They kept the vehicle and fiddled with it for like 2 weeks. The CEL went away for 6 months and came back this time solid and not going away anymore. I took it back, they said the exhaust system was "loose" and tightened up all the connections, CEL came back right away. I suggested electrical since it was intermittent and we've done everything else. They checked and said electrical was OK. They then said everything was fine with the engine and the computer needed to be retuned to the new exhaust dynamics and said they couldn't help. Here's my question to any experts out there. Is that something that can be done and by who? Never did that before and it sounds like the "Tuner" would have to get into the computer and change some variables in it's database. It runs fine just makes me nervous that if something else goes wrong I'll never know until I get a failure. Any comments would be welcomed.