My CEL was on about 3 weeks ago and I assumed it was my MAF (as it always is) so I removed the filter to clean it, cleaned the MAF and installed the paper filter. I hadn't re-oiled the Amsoil filter yet (busy, lazy, take your pick) when the CEL came on after a few hundred miles. I thought it best to pull the code before assuming I had done a lousy job cleaning the MAF and received P0420, "Catalyst System Efficiency Below Threshold (Bank 1)" (thank you, Autozone).

The dealership confirmed it, checked and then replaced the catalytic converter. I was in and out of the shop in 1 1/4 hours. Since it's covered under the 80,000 mile emmisions warranty and I have ~75,000 on the rig, my total bill was $0.00

 

that worked well. good to hear. thanks for the info.