This past week on my '07 the #4 plug wire had worked loose and I got an engine light flash and chime. The key dance gave a code of P0052. No misfire code(s) but I believe that is the only condition that causes your engine light to flash and chime. I fixed the plug wire but the engine was still misfiring under load. The Jeep was not drivable ... it seemed to be totally cutting out the fuel when I got on the throttle.

I did the key dance and got a P0052 again. Still I thought a wire issues but it would only start misfiring after the warm up period. Not having the proper tools on hand to properly diagnose I disconnected the 02 sensor and no misfiring under load after warm up. You do not want to really do this for long though, I think it runs rich and could destroy the cats on an extended drive. My guess was some sort of erratic rich signal was being read from the sensor after the warm up period and causing the fuel to cut out.

So I guess the wire related misfire killed the 02 sensor which then introduced a new misfire all it's own. Confusing as heck, a rich misfire to start the problem and left behind a lean misfire.

I picked up a Bosch 15122 for $27 (as low as $21 on the interwebs). I heard people are using the $100 NTKs as Bosch sensors do not work well. The damaged factory sensor I pulled ended up being identical to the new Bosch 15122 I purchased. Identical as in the exact same sensor ... same construction, markings, wiring, connector. Code is gone now and Jeep is running great.

Matt