P0420: Do I need a new catalytic converter?

[AaronPaul]

In my 9 years experience working on cars and trucks, I have never seen a p0420 or p0430 be caused by anything but a cat.

Mind if I ask you about this?

 

[j33pster87]

Has the vehicle been driven hard since the other issues? If not, carbon and other deposits can build up on the catalyst and reduce its efficiency. If it hasn't been run hard, a long Italian tuneup might be a good way to try and clean it out. The idea would be to get the catalytic converters as hot as possible. If you can find a freeway that allows 75+ and do a lot of hard acceleration or fast hill climbs, that should burn up any deposits.

If that doesn't do anything, it may be worth replacing the catalytic converters. I replaced mine with a bolt in Magnaflow unit. It wasn't cheap but it fit perfectly and has given me zero issues.

Does your direct fit magnaflow catalytic converters have any heat shield. I bought some and was told they don't need heat shield there built to be without it. Just has me worried for everything that sits around them once they heat up

 

[Steel City 06]

Does your direct fit magnaflow catalytic converters have any heat shield. I bought some and was told they don't need heat shield there built to be without it. Just has me worried for everything that sits around them once they heat up

The 3rd cat has one. The two pre-cats do not, but it has never been an issue for me. I think insulating the exhaust header would have a bigger impact than the catalytic converters.