2003 Tribute 120K showing P0420 code. No problem with engine performance. Seems to run fine. Should I be expecting a catalytic converter issue at this age and mileage? Is a catalytic converter cleaner gas additive worth doing? Does that stuff really work? If so, suggested brands?

 

The CAT is likely at it point of needing to be replaced. The chemical CAT cleaners really do not work on a CAT with that many miles. The health of a CAT is directly repeated to how well the engine was kept up,i.e. oil and sparkplug changes.

If it were me and I say "ME" I would try to run water through the intake system and give the CAT a steam bath. If you do not understand how to to do this then DON"T!

You can look up the attributes of water injection and also "old school" techniques to quickly clean carbon deposits in the intake, combustion and exhaust system of a gasoline engine. As far as I am aware of I have NEVER been schooled in any training class and have never seen it on a test for certification a question about water injection? So anything you do you do at your own risk !

 

Well, I cleared the code and, in a week, it hasn't come back. Maybe it wasn't that serious about it? Also, I later ran some Cataclean through it. I'll just hold my breath and hope it's not an issue anymore.

 

 

Well, OK. I turned off the code, and for a week it didn't come back on. Then I Catacleaned, and it still hasn't come back on. I'm keeping my fingers crossed, and will run another Cataclean in a few months.