I have not had any of the recent service recalls done, so hopefully that is not my problem. I was out wheeling/hunting the other day and in four low. I went through a large mud hole which had been frozen over in the morning. Now that the sun was out, it was pure mud. I had been through this particular hole many times before in prior years with no issues. This time, apparently enough mud had been thrown out by others that I found a large rock with my rock sliders. I also heard a loud bang on the passengers side (opposite where the rock was) and my "service 4WD system" warning light came on. I backed out of the hole and checked underneath. Nothing visible. Turned the Jeep off/on and the code reset. Drove forward, the warning activated again. I shifted out of 4 low, turned the engine off/on and it reset and did NOT come back on. I shifted back into 4-low and the warning came on again. Obviously this is a 4-low related issue. I came home and checked DTC codes. The only one was p 171 which appears to be an unrelated fuel system code. Where do I even start to try to figure out what is wrong? No codes, nothing appears broken, nothing abnormal other than the warning. Thoughts besides take it to the dealer?