2020 GMC Sierra 2500HD Error Code P20EE

slimjim7772 · September 24, 2019

Purchased a brand new 2020 Sierra 2500HD 6.6L Diesel. The truck had ~400 miles on it when I left the dealership. I drove it for ~200 miles and the check engine light came on. Called Onstar for a diagnosis and they told me it was a P20EE error code. Took it to the dealer and was told this was a known issue and there was no solution although they had a Service Bulletin that said to reset the sensors, set it up for a regen and clear the code. The dealer said the code may or may not come back on. The next day the check engine light came on and I called Onstar again. They told me the same code P20EE. Called the dealer and was told to continue driving it, they said it would not hurt anything else and as long as the truck was running okay then everything was okay. In my opinion if the check engine light is on then the truck is not running okay. Contacted the GM Service Center and was told the same thing, that GM is working on a solution and to keep driving it until GM can resolve.

Now a couple of question: Has anyone else had this happen? Will it cause any damage or other issues in the future if I continue to drive the truck?

BB&Chiveon · September 24, 2019

everybody has had it . on many many posts

slimjim7772 · September 24, 2019

Okay...I guess I can’t find the “many many” posts. So I guess the answer to my first question is “yes”, that’s simple. But what about the second question? Since you have seen/read many many posts maybe you could be helpful and answer it.

sdelam · September 24, 2019

I've seen several posts for it. Some here, more on the duramax forum, and on a Banks idash facebook group. All have got the same result from dealers, reset, ignore and drive. Down side is that with a check engine light on, your remote start will be disabled. I have been fortunate, 5 k miles without an issue. (Knocks on wood).

Someone posted a copy of the service bulletin for reference.

Edited September 24, 2019 by sdelam

Shawn T · September 24, 2019

Mine is going back in again next week. All the dealer does is clear the code and give it back, what a hassle. Mine SES light was on for 3 days and went off yesterday. What sucks is that while we are waiting for GM to fix this we have not remove start via the key fob or the MyGMC app.

https://www.gm-trucks.com/forums/topic/226839-check-engine-light/page/2/#comments

BB&Chiveon · September 24, 2019

8 hours ago, slimjim7772 said:

Okay...I guess I can’t find the “many many” posts. So I guess the answer to my first question is “yes”, that’s simple. But what about the second question? Since you have seen/read many many posts maybe you could be helpful and answer it.

powerhaulic · September 30, 2019

i have had P0700, general trans code. It is a loss of communication between modules, truck operated fine.

I also have a Banks Idash, nice to have as i can usually clear and check codes with it.

Shawn T · October 1, 2019

Picked it up last night, the current solution is a software update. They reset the NOx sensor and uploaded the software, not fully confident it will work but I imagine the software update may take a few revisions.

Chad Langford · October 1, 2019

Been having the same issue. They updated the code yesterday we'll see if it corrected the problem

Chad Langford · October 4, 2019

Have the code updated Monday waiting to see

BB&Chiveon · October 4, 2019

took to dealer today and got the fix , dealer was also doing his trucks on lot

DVohs3 · October 9, 2019

I had this same problem with mine too. About 750 miles and it came on. It used a half tank of def in that time period too. Has anyone else had the extreme def usage too?

DVohs3 · October 10, 2019

I had this same problem with mine too. About 750 miles and it came on. It used a half tank of def in that time period too. Has anyone else had the extreme def usage too?
UPDATE: Took my truck to the dealership and they said that there was a recall (tsb) for the def system. They reset the check engine light and flashed the ecm with an updated software. I’ll do another update if it comes back or if it stays off for a month or so.

xsvn2o · October 15, 2019

Mine has 6000 miles on it . Its been using a ton of DEF (30 plus gal so far) . after a few dealer visits I am about ready to try a ford .

davester · October 15, 2019

On 9/30/2019 at 5:37 AM, powerhaulic said:

i have had P0700, general trans code. It is a loss of communication between modules, truck operated fine.

I also have a Banks Idash, nice to have as i can usually clear and check codes with it.

P0700 is just a generic error code meaning "the tcm has signaled the ecm that it's noticed a problem".

You need a more advanced code reader to get codes from the TCM, indicating the actual problem...