6.6LML bucket of DTC's - help please


New member
May 11, 2022

Please see vehicle information attached (year, make, VIN), and other info about mods, mileage, purchase date. Codes are being thrown primarily during a tow scenario; 11k lb bumper pull toy hauler (as weighed at scale fully loaded), and a 1200 lb bass tracker.

I have recorded the last 10 DTC events in hopes that I can get a second opinion, other than the dealerships direction to “replace EGR valve, NOX #1 sensor, and the MAF sensor”, with the caveat that if codes come back, bring the truck back for further diagnosis. That to me sounds like guess work, and Im not willing to pay $2500.00 (for a guess). All DTC events have been cleared, with exception to #10.


Common theme in every event, is DTC P2453 DPF Sensor “A” Circuit. I do not know the last time (if ever) that the DPF was replaced. I do know that is regens (per CTS3) on a regular basis, which I have recorded as about every 300-400 miles (while towing), maybe every 120 miles while driving in town (unloaded).

Event #2, occurred just after dealer serviced all fluids and filters. Those codes were present before, so I am not saying the dealer jacked anything up. Just providing that for reference as a baseline overall vehicle service date.

Event #3 I cleaned the MAF with MAF cleaner, thinking the sensor may have gotten some K&N oil on it. I was able to drive truck about 300 miles or so, before the P0101 code came back in event #6. Re-cleaned, cleared, and then DTC P0101 back on again a few miles later.

Event #9 was concerning as I noted an immediate EGT #1 temp spike while towing. EGT #1 temp holds steady at about 800 degrees (towing on highway loaded), then code threw and temp spiked to about 1100 degrees with “reduced engine power” notice on instrument panel. At same time I also noted trans fluid temp rising to a max of about 220. EGT #1 temp dropped back to normal about 10 miles later, trans temp back to normal (140-180) about 30 miles later. All codes cleared, never experienced reduced power.

Another 20 miles later event #10 occurred, temps normal. Parked ever since.

I understand this is a lot to digest, and I may have forgotten to include details needed to properly diagnose. I have not gone back to a paper air filter, but I have checked most of the wiring harness (the places I can get to), and have not noted any chaffing or issues. Looking forward to professional input and systematic approach to correct.


Well-known member
Dec 15, 2010
any tuning, mods, edge modules installed or boost foolers? I'd start by at least putting the stock filter back in to eliminate the oil on maf issue. oil affects air reading, air reading affect fueling, fueling affect EGT, boost, and a few others.

you may also need to do some logging too so you can see what event occurs before the codes pop up

go through this document and double check everything is ok


Ron Nielson

Active member
Oct 11, 2009
Berryton, KS
See attachment. This pertains specifically to my 2008 LMM and I think that the MAPs were changed somewhat since then. But that's the best info I have and probably still good in a basic sense. Not being able to correctly calculate the 'boost' can be a real problem in getting the engine to run correctly.

Also see here https://www.dtcdecode.com/Chevrolet/P0106 I didn't check to see what other codes are in this file. Lots of good reading material and lots of things to check or consider.


  • P0108.pdf
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