Check engine came on Sunday morning the code that through was P0 526 u062F. After calling the dealer and setting maintenance to be done one day later, the truck broke down while driving on the side of the road. The dealer is saying that the belt came off and the tensioner locked up doing damage to the fan clutch and connector. The case, because the code that ran is saying that the belt wasn-€™t going the speed that it was supposed to because the tensioner failed. The vehicle only has 55,000 miles on it.

- Bowling Green, KY, USA

I took my vehicle into the local dealership two weeks ago for the DPF emissions voluntary recall. Prior to the service I was getting 16.6 mpg for the 42000 miles on my truck. After the service, for the ~200 miles driven on same route and conditions commuting to and from work I have only been able to achieve ~13 mpg. There has been no other changes to my vehicle or operating conditions. When I took the vehicle in the advisor mentioned that it may take awhile for the service because -€œwe have to download the update wirelessly.-€ While researching this issue the recall document specifically warns against wireless download of the update. I am not sure if this may be the result of not following the correct process or not and I am headed back to the dealer today. I also found several others posting on the diesel forums about similar significant loss of mpg after the update. Losing almost 25% fuel efficiency after the update is unacceptable and reflects the my previous experience of efficiency loss during an actual regeneration cycle prior to the update. The vehicle is acting as if it is running in a constant regeneration cycle. Unsure if this may lead to dangerous driving condition due to excessive stress and wear on the affected parts and engine.

- San Antonio, TX, USA

DEF system failed. Wire harness burned out. Tank failure. Truck went into limp mode. I personally know 3 others with the same issue.

- Middletown , NY, USA

Truck has had multiple issues related to the electrical system and truck modules. It is my opinion that these are all related to voltage issues or module problems. i have had multiple infotainment issues with delays loading, freezing up etc. dealer has ran updates and checks with nothing found. In October around $35k miles the truck Radio would not work if i used the push button start. if i shut the truck off opened the door and let everything reset i could push the start button in the truck and the radio would work majority of the time. The next day i went out to a completely dead truck. I talked to my service department at the local dealer and they said i would need to bring it in but suggested i disconnect the batteries and recharge the batteries. after doing so everything started working correctly. it fixed my radio problem and never went dead again. since then i have experienced popping noises through the speakers when playing music occasionally. over the last few weeks i noticed the engine does not attempt to increase cold idle speed until i press the brake to put it in gear. January 22nd i hit the autostart button and it did not work. i started the truck and it had CEL, Traction control, park brake and wrench, lights on with service emissions, and power reduced messages displayed. Truck is running odd. codes present are (ENGINE GMLAN)P0118 - engine coolant temp circuit high voltage, (BRAKES GMLAN_ABS) U0401- invalid data from engine control module, P0562- system voltage low, (HVAC CONTROLS GMLAN_HVAC) B1325 -. control module power circuit. Truck is starting and charging fine. No connection issues at batteries. There are many TSB's and many complaints regarding similar issues. common brake and emissions faults with minor differences. Module failures, communication faults, and or electrical faults are likely causing all of these similar issues. they need to be categorized as the same failure group which will show GM has a bigger issue.

- Shawnee, KS, USA

As I was driving home my check engine light came on and all of my lights went out. I had no tail lights and the radio started saying no signal detected. The dash screen was saying service keyless entry system. And I had no running lights but my headlights. Pretty scary thinking no one could see me as they were driving behind me at a high rate of speed. My truck only has 200 miles on it so this is really scary to be having issues so early in the ownership of this truck. I've always had Ford but this truck caught my eye and I stepped out of my comfort zone and now wishing I would have stayed in in.

- Washington, MI, USA

The contact owns a 2020 GMC Sierra 2500. The contact stated that while driving, he noticed smoke entering the vehicle through the air vents. The contact coasted to the side of the road, exited the vehicle safely with his passenger, upon opening the hood noticed that the whole engine compartment was on fire. The contact stated that the fire department arrived but was unable to extinguish the flames as they allowed the vehicle to burn until the fire self extinguished. The dealer nor the manufacturer was made aware of the failure. The failure mileage was approximately 2,800. VIN was not available.

- Sturgis, SD, USA