Second failed catalytic converter Bank 1 on 2004 Yukon

[PNWYukon]

Has anyone else experienced failed cats on bank 1? The original stock cats failed a while back, with a broken piece rattling around. The second set was a cheap brand from Rockauto and again bank 1 failed by plugging solid. Any thoughts or suggestions of what the causes might be will be appreciated.

 

[Fless]

Unburned fuel (bank running rich) and burning engine coolant can ruin a cat. Some chemicals used as gasket sealant can also degrade cats.

 

[Chevymec]

Any misifres or burning oil?

 

[PNWYukon]

Any misifres or burning oil?

Not burning oil. Sounds fine idling and at speed after cat replacement. Also have the 862 heads, so not sure about coolant burn. Just did a quick spray of carb cleaner to see if there are any vacuum leaks. It didn't change the idle or I didn't spray enough in the right areas, so I want to do a smoke test next to be sure I don't have a vacuum leak. I do have an EVAP leak on going to find as well.

 

[Fless]

Check your short- and long-term fuel trims at idle, then at 1800 or 2k rpm. Post them here for comment.

 

[nonickatall]

Not burning oil. Sounds fine idling and at speed after cat replacement. Also have the 862 heads, so not sure about coolant burn. Just did a quick spray of carb cleaner to see if there are any vacuum leaks. It didn't change the idle or I didn't spray enough in the right areas, so I want to do a smoke test next to be sure I don't have a vacuum leak. I do have an EVAP leak on going to find as well.

You can forget to find a vacuum leak with carb cleaner. That's my experience I bought a unit to run a smoke test and I found out that my car that I had a leaking o-ring at the oil dipstick.

But apart from that, I don't think that your problem comes from a vacuum leak.

The most likely reasons for the cat failure
1. Unburned gasoline which can happen when you have a leaking injector. When the car drops fuel into the system and the micro explosions your have in the cat destroyce the ceramic. Do you have while start sometimes the feel that the engine not firers from the first revolution?
2. Leaking coolant, but you should have missing coolant which you have to refill
3. Just a coincidence

 

[West 1]

I think you have great advice above already, my guess, the factory cat failed due to an engine issue, Cat was replaced but the bad engine issue remained and has now ruined 2 cats. Short and long term fuel trims tell you a lot but also watch the O2 sensors from cold start till fully warmed up. Watch them at idle and then watch them while driving. Study sensor 1 graphs for both bank one and bank 2. My guess is bank 1 will be wonky rich and bank 2 probably looks good since that cat is still working.
Has the engine been using coolant??? Coolant in a good truck does not change in level. You could jump in and drive from California to New York and back hard and the coolant level should not change at all. If you are adding coolant, even a pint every 5,000 miles it tells you there is a leak that needs to be fixed.

I fixed a Duramax a while back, the owner carried 2 gallons of Coolant in the back of the truck. I asked him why, he said because his truck has always used about a quart between fuel stops? He thought that was OK and Normal. It is not. Coolant should not be consumed by the engine. Found he had a leaking injector, coolant was leaking past the injector into one cylinder and was not enough to hydrolock the engine but when I pulled that head the chamber and piston head was steam cleaned from coolant getting into it while running.