P0430 after Lifters replaced

DCazares · March 23, 2022

I had a collapsed lifter and I had them replaced on the passenger side of the engine. Now after getting the truck back I have code P0430 (bank 2 cat deficiency). Is there a chance that the cat just needs to burn off any coolant that might have been spilled into the exhaust when the head was pulled or do you think the actual Cat converter is now bad? Tips on how to tackle it? I will take off the o2 sensors on bank 2 and inspect them before anything else. I already checked voltage to and resistance on the sensors and both of those check out.

14burrito · March 23, 2022

1 hour ago, DCazares said:

I had a collapsed lifter and I had them replaced on the passenger side of the engine. Now after getting the truck back I have code P0430 (bank 2 cat deficiency). Is there a chance that the cat just needs to burn off any coolant that might have been spilled into the exhaust when the head was pulled or do you think the actual Cat converter is now bad? Tips on how to tackle it? I will take off the o2 sensors on bank 2 and inspect them before anything else. I already checked voltage to and resistance on the sensors and both of those check out.

I know wiring and resistance checked OK but you able to swap post cat sensors between banks? If the fault goes to 1, sensors reading incorrectly. Stays in 2, further diagnose.

DCazares · March 23, 2022

I will do this tonight and check to see if it follows it to bank 1.

DCazares · March 24, 2022

I swapped the downstream o2 sensors last night and went on a 15 min drive on the highway, as soon as I let off to exit the CEL came back on. Same P0430 for bank 2 so the sensors aren't the problem. I'm sure the catalytic converter for bank 2 is bad. Pics of o2 sensors below, I noticed the bank 2 sensor was cleaner than the bank 1 which I though was odd.

Bank 1 left vs bank 2 on right

Thoughts on replacement options?

I found a set that was supposedly removed at 9k miles from a 2018 to be replaced with long tube headers. How would I check them visually to verify? Do I remove mine and inspect before I purchase anything?

Thanks for the input.

14burrito · March 24, 2022

IMO, Only thing would be to check the monolith / cone for proper honeycomb without much wear or clogging.

Have you yet tried doing a hot run / cat burn off procedure? Everytime I do a seafoam procedure, I follow it with a high RPM run on the freeway for 10/15min. Drop down the gears, get the RPMs high and cruise on the freeway for a while.

DCazares · March 24, 2022

I'll try that tonight. Thanks

DCazares · March 24, 2022

I forgot to mention, after the drive, I used an infrared gun to check the temperatures of the cats while it was still on, bank 1 cat was at ~210 degrees and bank 2 at ~250 degrees.

DCazares · March 29, 2022

OEM Cats are on back order with no eta from GM. Any recommendations on aftermarket that will work like oem and keep the CEL off? Magnaflow cats a good option?

CamGTP · March 30, 2022

Space the rear o2 sensor out of the exhaust stream a little bit, that is an easy thing to try to see if the code will go away. I call it the spark plug non-fouler trick, those are the same thread as a oxygen sensor. You can google/youtube video's on what to do, only cost you a few bucks to try.

OscarEChavez · March 8

did you ever figure out the issue? i’m having the same problem now

DCazares · April 18

On 3/7/2023 at 10:10 PM, OscarEChavez said:

did you ever figure out the issue? i’m having the same problem now

Yes, One Catalytic converter was clogged. Had to replace the Y-Pipe. Luckily I found someone local who had a y-pipe with both cats with 9k miles on them so I swapped those in. No problem since.

JONBLARC7 · April 20

Mind if I ask how much you paid for the Y pipe. I have one under the house I could let go since the way my exhaust is now. It can never go back on this truck.