Last night my CEL came on. Got the dreaded P0306 code. I have noticed a bit more ticking recently but wasnt worried until the CEL came on. Its got just under 28,000 miles so I guess mine lasted longer than many others. Its going in today and im hoping they dont try to give me the run around, and just replace the head. 3 heater cores, a radiator and now the cylinder head.. but I still love my jeep...