P20B9 and 160km until 104km/hr

That code is related to the DEF reservoir heater. It's usually accompanied previously by P21dd when the heater itself is bad. Since P20B9 is an open circuit code, you could have had an immediate failure of the heater or the module which controls it or the related wiring. Looks like you're still under B2B warranty, so you should have no problem with coverage or the loaner car, if your warranty details are the same as the U.S. Even outside of the B2B warranty, this would be covered under the 10 year/120,000 mile special coverage, this would continue to be covered, as long as it turned out to be a problem with the reservoir or one of its integrated components.

It seems to be a common issue. The DEF tank heater also quit in mine. They replaced the whole DEF tank. Mine has B2B until February 2021 or 160,000 km's, so thankfully mine was covered. I think mine went around 68,000 km's.

It will be covered under the extended warranty as stated above, I had mine done a couple months ago at 82,000km. Been good for over 5,000km and I gained a little on the MPG after the NOx recall work was done at the same time.

I really do hate that GM only gave 160km/100miles on the limp mode count down over an emissions issue though. Really unsafe in my opinion, what if you are in the middle of nowhere or have to get home from a road trip. That distance in not very far, they should have given a timer countdown like a week to service instead of a distance.

46,300 miles and mine screen just went into the SERVICE EXHAUST FLUID SYSTEM, and then the count down started. Same code as above. Going to the dealer tomorrow. Gonna have the NOX sensor recall done also.

p21dd, and p20b9 reductant heater A control circuit / open

Update... They replaced the def tank same day I went to service, they were on top and beyond on this service.

Also the mistery P11DC code is related to Nox position 2 sensor current performance. There is an updated part which they ordered. I have to go back next week to have it replaced, and it's covered under car basic warranty. Hope this will end the codes for a while.

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Got them both covered under a recall.

After a re flash mine did a similar thing. I posted this back in June

"I took mine in for a CEL P2453. They did the recall and the flash also a manual regen. When I picked up the car my Scangage said STM 3. I drove about 1 mile and it started a regen. The car started to buck and the CEL came back on. The service department was closed so I continued to drive. The STM went to zero but did not stop the regen (exhaust temp 1100) I kept driving until the regen stopped after 37 miles at STM 0 it finally stopped. Last night I took it out again and the STM stayed at 0 for 33 miles before going to STM 1. Very strange! I am going to wait a few days before taking it back to the dealer. The CEL will probably go off soon."

I'm still dealing with the bucking during regens, however they now start at 3 and go to 22 SM on the scangage.