So, we did the DEQ on my truck last week and came out clean as a whistle. Yesterday my Service engine soon light came on. Ran to Auto Zone for a check and comes up my cat on my R. bank has low efficiency in bank 2. Catalytic converter defective. Possible causes Engine misfire, large vacuum leak, oil leak into exhaust guides, piston rings. So, I don't know where to start. Hoping someone has tackled this problem and was successful. I do have an exhaust leak somewhere I've yet to try and hunt down. It's coming from under the hood. Maybe this could be the issue?
2000 F150, 5.4L, 138k miles, auto, 4x4, Dealer says engine was replaced 5k miles ago. Of course there's no proof.