2020 GMC Sierra 1500 Body & structure Problems

The frame of the back window is cracking allowing water to come in through the back glass. This is causing the headliner and other components such as air bags and other electrical components to get wet and damaged. This could cause risk of fire or failure of safety components within the vehicle such as air bags, cameras and other sensors. With water intrusion comes the high risk for mold to develop and cause serious health risks. GMC is aware of this issue and will not agree to repair it. A GMC dealer has inspected the glass and said it was a faulty seal but since it's not in the 3 year warranty window, it's not covered. Independent auto glass companies state they have seen this issue many times and the glass seal is faulty. GMC should do the right thing and fix this issue. This devalues the vehicle and the GMC brand and poses serious risks to driver. I have created a case with GMC and submitted photos, videos and dealership estimates for proof.

NHTSA ID

11726576

Incident

Nov 30, 2025

My multipro tailgate on my 2020 GMC Sierra 1500 unlatched while a trailer was attached and backing up said trailer. The trailer jack post proceeded to buckle the upper part of the tailgate assembly causing extensive damage resulting in over a three thousand dollar repair bill. If the tailgate had released while a child was in close proximity, serious injury may occur. The tailgate has inadvertently released twice in the five plus years I have owned it, the first time as I was traveling down a highway at over 60 mph. This could have endangered a vehicle to my rear if cargo had been released on to the road. I have reached out to a local dealership for repairs and assessment, no real way of troubleshooting something that has happened twice in five plus years. The scan did not show any codes. the info center does notify you if it is released but not before it takes place and after the fact may be too late in some circumstances as it was during the second occurrence. There has been a recall on 2500 and 3500 models with the exact same tailgate but not the 1500 models. 820K vehicles affected but not on the 1500's.

NHTSA ID

11672898

Incident

Jun 19, 2025

Had water leaking into cab of truck. First incident they stated it was a rear window seal and it was "repaired" under warranty. Second incident I was advised it was body panel separation where the cab roof and side body seam was leaking. It was repaired by sealing with "body seam sealer." I later read these repairs should have been welded. This was after the warranty expired and I had to pay for it. I then read on the Silverado/Sierra forum this repair should have been a weld not just "glued" is this a safety issue?

NHTSA ID

11656171

Incident

Mar 27, 2024

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the parking brake was independently activated. In addition, the contact stated that the vehicle had an oil leak from the oil pan. The contact stated that the oil needed to be added every two days. The contact stated that the alert system warning light was illuminated. The vehicle was taken to the dealer; however, the failure was not duplicated. The contact was informed that the failure could not be duplicated, because no active codes were retrieved. In addition, the contact stated that the frame had corrosion. The vehicle was taken to the dealer for corrosion failure, however, the contact stated that the previous dealer had failed to help. The dealer confirmed the corrosion; however, the vehicle was not repaired. The manufacturer was made aware of the failure but provided no assistance. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 10,000.

NHTSA ID

11646779

Incident

Mar 6, 2020

Mileage

10,000 mi

Tailgate opened on highway with cargo in bed. Also tailgate opens randomly when parked. This has happened many times, creating very dangerous and unexpected situations Numerous contacts to the manufacturer have been unsuccessful in getting the hazard placed on recall. Numerous incidents. Keeps happening

NHTSA ID

11643561

Incident

Feb 18, 2025

Tailgate releases on its own while parked, without the use of the switch. Tailgate released on its own with my trailer attached while parked on many occasions. The result of the Tailgate releasing caused damage to the upper section of the Tailgate, the "kicker speaker system" in the Tailgate and Tailgate switch located on the upper section of the Tailgate. There also have been multiple times when attaching the trailer that the Tailgate has released and struck me in the head. The Tailgate also fills with water during rain, and carwashes. The damage caused by the Tailgate releasing is a dent on the upper section of the multi-pro Tailgate and rust and malfunction of the " kicker speaker system " as well as the occasional hickey and headache on my head. The Tailgate has filled up with water since I purchased it new in December of 2020 which I believe has been electricly shorting the Tailgate switch/button releasing the Tailgate randomly. Due to my particular 2020 GMC Sierra 1500 AT4 CarbonPro having the " kicker speaker system " in my opinion makes the Tailgate so much heavier than one without it that it made the damages such as the dent in the face above the Tailgate switch much worse than trucks without it also causing more water to enter the Tailgate causing more damage to the switch and components of the " kicker speaker system ", such as the amp and buttons for it not to mention my head on several occasions.

NHTSA ID

11628811

Incident

Dec 1, 2021

The rear sliding window leaks water inside the cab every time it rains. With water getting into the cab the issue of mold has begun and that could be a serious factor to any children or adults that ride inside the cab of the truck. There is also rust issues that are notable under the rear seats of the vehicle. Water inside the cab can also interact negatively with any electrical components of the vehicle. I tried to get ahold of the dealer and they always say they don't have time to get my truck in. I have read that this has happened to other vehicles that are the same year and model and they just fix it with caulk which does not seem appropriate for a almost new vehicle. The vehicle has not been inspected. There were no warning lamps prior to this issue. A possible symptom was that my back up camera stopped working for a day right after a rain.

NHTSA ID

11586345

Incident

Mar 9, 2022

Rear window leak causing whole inside back to get soaked. Have paid hundreds of dollars to have sealed didn’t work. New window didn’t work it still leaks. It’s going to cause interior to mold and body to rust. Dealership and glass business both say it’s body issue and they have seen many GMC and Chevrolets with this issue. Google show 1000s with same problem.

NHTSA ID

11581595

Incident

Nov 3, 2023

GM refuses to fix a known design flaw in the back sliding glass frame on 2020_24 gmc sierra trucks. This issue will generate toxic mold as large quantities of water enter the cabin and can be extremely harmful for certain individuals allergic to mold. GM knows about this issue and tried to secretly advise techs via TSB 18-na-383 to apply sealant on the frame and if customer returns to replace frame. However they do not want to do this outside the 3 year warranty. The back glass on a truck is not a serviceable item.

NHTSA ID

11580419

Incident

Apr 1, 2024

Rear Sliding Glass window frame has cracked and allows water to enter the cab of the vehicle. Yes this is available for inspection. The water entering the cab of the vehicle can create mold from moisture build up if left untreated. I was able to have the dealer service center confirm the issue noted in [XXX] but they were unable to repair it as it is outside of warranty. I was able to have an independent 3rd party glass company confirm that it was indeed a manufacturers defect with a cracked housing and not an issue with sealant around the glass itself. No warning lamps or other indications other than water in the back seat of the vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11572789

Incident

Jan 29, 2024

Rear Window Leaks due to failed sealing at the factory. If not fixed will ruin interior components and possibly rust. Yes No No

NHTSA ID

11572201

Incident

Dec 9, 2023

The back window leaks, I brought it in they told me it wasn't warranty so I paid to have it fixed. Still leaks.

NHTSA ID

11569648

Incident

May 14, 2020