2021 Chevrolet Silverado 2500 Electrical Problems

The contact owns a 2021 Chevrolet Silverado 2500. The contact stated that the connector for the heater system was causing the vehicle to overheat, subsequently enabling the vehicle to go faster than 50 MPH. If the vehicle reaches 75 miles, it would immediately decrease in speed to 5 MPH. The vehicle was taken to a certified mechanic who diagnosed a P20C1 code, indicating reductant heater failure had occurred. The vehicle was not repaired. The contact called the dealer, who recommended calling the NHTSA Hotline to file a safety complaint. The manufacturer was informed of the failure they also referred the contact to the NHTSA Hotline to file a safety complaint. The failure mileage was approximately 68,000.

NHTSA ID

11704659

Incident

Dec 10, 2025

Mileage

68,000 mi

We believe that it is the park sensor in the column . When you place the truck into park, the screen displays the words shift to park period and the dinger.Inside the truck continues to ding for a long time, even with opening and closing the door ... The truck is actually in park, so it does not move.But the display says it's not.And apparently it is not registering because it keeps dinging

NHTSA ID

11695209

Incident

Oct 23, 2025

The tailgate on my truck is electrically opened & closed. I've been having trouble with the tailgate opening randomly, even while driving. This has happened multiple times and can create a very dangerous situation, especially if i'm hauling something in the bed of the truck and it could possibly fall out if the tailgate were to open. Once i was hauling a bunk bed and the tailgate opened without me knowing it. Fortunately, we were driving through town on a flat road when it happened & nothing fell out. Someone behind me pulled up beside me to let me know my tailgate just opened. I recently took my truck to my local Chevy dealer & they said there was no recall on it & they wanted $170 for them just to look at it. I looked online and see recall# N232426400 for it but i've never received a notice & the dealer says there is no recall on it for my truck. (I have a video of it opening & closing by itself but it's too large to send you)

NHTSA ID

11679809

Incident

Jun 2, 2025

The tailgate on our truck keeps automatically coming down and up on its own. It doesn’t matter if the truck is in park or drive. It doesn’t matter if it’s locked or unlocked. It will do it several times in a row. It will go half way back up and then just slam down. Unfortunately we didn’t know this was an issue as we just bought the truck a few days before we noticed it happening and it fell down and hit something in our garage causing a dent and multiple scratches as it happened overnight without us being aware of the issue. It happens when I’m going down the road, which means I cannot use the bed of my truck as things could fall out. Also, I’m limited on where I can park it. We called GM and a dealership and there’s nothing they can do since it’s not recalled unless we pay to have it fixed. So now we have a new to us truck that’s now dented because of this issue. There is no warning it’s going to happen. After the tailgate comes down I get a notification saying tailgate down when I’m driving. This happens everyday, several times a day and we’re having to avoid driving it when possible due to this issue.

NHTSA ID

11652897

Incident

Mar 31, 2025

RECEIVING SERVICE TRAILER BRAKE SYSTEM. SEEMS THIS IS A KNOWN ISSUE WITH TRUCK AND SHOULD BE A RECALL THAT GM FIX AND NOT PUT ONTO CUSTOMER

NHTSA ID

11652715

Incident

Mar 3, 2025

In certain GMC and Chevrolet Models 2019 to 2025 it is common knowledge and easily found on the web that there is a manufacturer defect that does not allow the vehicle to be placed in “park” properly due to defective parts in the steering column that do not allow the vehicle to safely turn off fully. The module does not seat and the vehicle will remain on in auxiliary. https://m.youtube.com/watch?v=RTcX-j3R5OQ . Again the link is an example but this defect is rampant.

NHTSA ID

11640944

Incident

Feb 5, 2025

Engine Code P10D9. Electrical harness to the DEF tank melted. My truck was not part of the GM recall but clearly effects more vehicles than they believe. See NHTSA report N212342980. Spoke with Chevy customer service today and they stated the wiring harness melting is not covered under warranty. This is a fire hazard that GM should remedy. The recall is clearly larger than 38,000 vehicles. Are we supposed to drive the vehicles and not know if they will catch fire or not? I spoke with a technician at Milnes Chevy in Imlay city today and he stated that he sees so many of these trucks that were not under the recall having the same issue with melted wiring harness.

NHTSA ID

11635680

Incident

Jan 11, 2025

The DEF heater short circuit and derates the truck. If the government says we have to have this they should cover the cost to fix it.

NHTSA ID

11635352

Incident

Jan 8, 2025

Tailgate automatically opens and closes on its own.

NHTSA ID

11597885

Incident

Jun 28, 2024

Tailgate opening and closing on its own. No input from key FOB, switch on tailgate, or switch inside of cab. No fuse indicated to pull to stop.

NHTSA ID

11593906

Incident

Jun 11, 2024

Tailgate. Yes it can be inspected. It opens and closes randomly , I was going on to the freeway for work when I suddenly received a notice that the tailgate was opening. when I pulled over the gate was open and all the contents were at the end of the truck bed, power saws and equipment almost flew out into traffic! I then called the dealer who told me there was a recall and to bring it in, so I did and when I pulled in the service department the tailgate opened upon entering service area. After about 20 minutes he tells me that mine is not covered. Warranty ran out! And not on that Vin#. The tailgate now opens and closes randomly at all different times.Try to close and it just keeps opening and closing.Have to go out and close manually.

NHTSA ID

11581794

Incident

Mar 28, 2024

Having issues with “Service Trailer Brake System “ , this should be a safety concern for GM , and not up to the customer to pay for this repair.

NHTSA ID

11559956

Incident

Dec 1, 2023

It's a known issue that 2020 and 2021 Chevy Silverados have a malfunction in the tailgate where it automatically opens while driving, opening the driver-side door, or even locking and unlocking the vehicle.

NHTSA ID

11554320

Incident

Nov 1, 2023

2021, Chevrolet Silverado 2500 HD, Crew-Cab, 6.6L Gas Engine. At @ 25k miles, the "Service 4WD" light came on dash. It later started a grinding noise/sound within the front axle transfer case. Was told they had a problem with moisture intrusion into the transfer case and it would cause corrosion to sensor. Truck was taken to dealership and in shop for @ 1 week or so. After repair was completed, less than 3k miles later, it happened again. Same problem ("Service 4WD"), same noises, same diagnoses. Truck was taken back to the dealership. This time, repairs were more extensive and the wiring harness was replaced. I was traveling with work yesterday (34,458 miles on truck now) and the "Service 4WD" light came on again. I've contacted the dealership to schedule a time at the end of week or early Saturday to take the truck back again. While reviewing other complaints, I noticed a similar problem where the customer indicated the "Service Tow System" light was coming on. It too was allegedly caused from moisture intrusion. I'm currently over 3 hours from home through the end of the week. I'm hoping the truck will make it home without creating a catastrophe on the Interstate between here and there.

NHTSA ID

11518758

Incident

Apr 23, 2023

The “Service Trailer Brake System” warning will not stop popping up and beeping

NHTSA ID

11502612

Incident

Jan 19, 2023

AFTER TWO WEEKS OF OWNERSHIP, THE REAR CAMERA HAS STOPPED WORKING. INSTEAD, I RECEIVE AN ERROR MESSAGE. THERE ARE NO SHORTAGE OF COMPLAINTS LIKE THIS ON VARIOUS MODEL CHEVROLET FORUMS. MOST 2020/2021 CUSTOMERS INDICATING THERE HAS NOT BEEN RESOLUTION OR SPECIFIC ISSUE IDENTIFIED.

NHTSA ID

11416218

Incident

May 11, 2021

Mileage

261 mi

6.6L GAS TRUCK WOULD NOT START. FORUMS IVE VISITED STATE THIS IS A KNOWN PROBLEM WITH THE ECM. AFTER APPROX 30MINS IT STARTED. HOWEVER BEFORE THAT IT SPUTTERED OUT EVERY TIME I WOULD TRY TO START IT. IT APPEARS TO BE AN INTERMITTENT PROBLEM. IT RAN FINE ONCE IT EVENTUALLY DID START. ALSO AUTO START WOULDN'T ENGAGE WHEN THIS PROBLEM WAS OCCURRING.

NHTSA ID

11388641

Incident

Jan 17, 2021

Mileage

1,656 mi