Help, My check engine light came on...went to Auto Zone to read the codes. The confusing thing is that PO340 is a cam sensor issue and I was told that my Jeep doesn't have one. Its a 99 Wrangler 4 cly. They though the scanner was reading a crank shaft sensor issue. Has anyone experienced this? They also thought that the throttle sensor issues (PO121 and PO123) were being caused by the PO340 issue. Anyone have any thoughts?