Can’t really help other than saying that there is a HP and LP EGR valve and a butterfly exhaust valve (passenger side, down near the frame). Not sure why you have a GP issue (other than it’s just coincidence)?

 

Yea I kind of assumed the GP was coincidental. The other codes are way more consistent.

 

Shouldn’t need to clean the EGR valve - the LP side is after the DPF, so it’s not getting soot in it.

Glow plug #2 and #3 can be affected by the valve cover with the improperly welded baffle. By chance is it using oil? There’s a TSB that shows how to look and see if the serial number on your valve cover is the old design. Also check Spicer Designs YouTube channel and on his most recent video about his ‘20 3.0 Duramax he talks about the issue and shows how you can check your valve cover #

 

Thanks for the advice! I just checked and it does have the serial number indicating it’s the old design. I should still be under the powertrain warranty so I called the dealer to have it looked at. I guess it’s not a stretch that this issue could also cause the exhaust codes?

 

Certainly possible - are you noticing oil usage - especially when towing? If not, then the dealer probably won't replace the valve cover. If you are using oil and the dealer is aware of that TSB, that's the first thing they should look into. I would also check the wiring going to and around the backpressure valve on the exhaust.

 

I got code P2B97 on my 2021 Sierra 1500. It took a couple of trips to the dealer but they replace 55514983 back pressure valve under warranty. I will report back if it does not stick.

 

Any luck?

 

All the GM service bulletin’s that I’ve seen on this cam cover/bad baffle weld are glow plug 2 and no P133A code (P06DD instead).

https://static.nhtsa.gov/odi/tsbs/2022/MC-10210839-0001.pdf

 

Did you fix your issue?