A buddy and I are trying to diagnose a DTC P0420. We swapped the downstream O2 sensors and the problem remained on bank 1 so we are pretty sure it is a bad catalytic converter. Seems like this is a fairly common problem. What are you guys using for a replacement catalytic converter. The truck this is going on is completely stock and we want to keep it that way. Cat-less is not an option. We are just looking for a cat that can easily take the place of an OEM. Does anyone have any ideas or tips? The truck is a 2005 2500HD ECSB 6.0L.

Thanks in advance.

Josh

 

From what I've seen (your not gonna like what I say) the only catalytic converters that can satisfy the GM standards are FROM GM.

Quite literally, you have to buy the catalytic converter from a chevrolet dealer. I have heard rumors that the magnaflow cats that are california rated (with the highest cell count or however they rate them) can work, since GM and other manufacturers build cars to be 50 state legal most of the time.

 

Considered tuning out the cats and rear o2s? That will fix it

 

GM cats ONLY, if you want the SES to stay off . . .

I own an auto repair shop, and we've found out the HARD way! Now we sell OEM cats only on OBD II vehicles.

Aftermarket cats, regardless of the brand, are too small (insufficient O2 storage capacity) to satisfy the OEM monitors.

 

I replaced the main cats with magnaflow hi-flows and cut out the pre-cats. It's been a year and it hasn't set any codes.

 

How in the hell does "tuning out the o2s" fix something that needs to be replaced? That would purely mask the problem and lead to eventual serious problems! Now if he gutted the cats and then decided to "tune the o2s out", that would be fine but, as stated by the OP, they want to keep it stock.

As for the OP. If you want to stay stock, as stated before, your pretty much stuck with getting the factory replacement from GM. You might be able to find a low mile factory take off from some one who went with long tubes and replaced the factory exhaust or a junk yard.

 

Thanks for all the responses guys. This is helpful information. I guess I will start cruising the classifieds section for an OE cat. I found some reasonably priced walker/dynomax "universals" from Summit that looked like they were about the correct dimensions, but it sounds like that is not an option.

Do you think it is hurting the truck at all driving around with a bad cat? When they fail it is due to being clogged or something else? Just curious.

 

Should be able to recoup some from the scrap value of the old cats.

 

Driving around with a clogged cat could be catastrophic if it is clogged enough. If the exhaust can't exit the the tail pipe, it will find somewhere else to go or just keep building up pressure until something gives way.......

 

how many miles do you have? that may still be covered under warrenty .. depending on how the cat failed will how long you can drive it but its not a good thing to push your luck especially with the expence of the cat repair