2023 GMC SIERRA 1500 Unknown Or Other Problems

Onstar module is out. No wifi, speed reporting or maps access.

OnStar quite working, light nothing. Called Onstar, told me I need to take to the dealer.

Tailgate can open by switch located at storage area in console. It can be easily bumped then tailgate will o pen without driver receiving a warning light or dashboard message. If this occurs, and it did with this vehicle, any cargo could potentially fall out causing accident to vehicles following. Additionally, the powertrain (transmission) is a known problem for failure. If such a failure occurs the rear wheels can lock up causing accidents/injury to driver and others. NOTE- this has not happened to this vehicle yet but does cause concern for it happening and GM not doing a recall.

The grille deflector suddenly detached from the truck and flew off into traffic. It narrowly missed the vehicle behind me and could have caused a serious accident or injury. There was no prior warning or impact that would explain the failure.

OnStar module in-operable, bought the vehicle expecting the system to work as it is another safety feature in case of an accident. Technical support will not continue to respond when contacted. Will not assist with any technical support to diagnose issue.

The Onstar system and Wifi connectivity stopped working over a week ago. The vehicle is less than two-years old, but it had three recalls which we took it in for this past week. We were told by the GMC dealership that one of the recalls would correct the problem with the Onstar and Wifi connectivity. However, it did not and now we are being told that the Onstar module needs to be replaced, and the dealer says it isn't under warranty. GMC has tied the warranty of the Onstar module to the miles instead of the time in-service. Many other customers are experiencing the same issue. GM markets Onstar as one of their safety features and as such repairs should be covered by the manufacturer.

In the past few months this truck has been worked on twice. First was the valve body and now it is the coolant control valve. These things have caused my truck to completely slow down or shut down without warning.

On [XXX], at approximately [XXX], while driving northbound on [XXX] between [XXX] and [XXX] (Austin, TX) at roughly 65 mph, I suddenly heard a loud cracking and popping sound from the front of the vehicle. As I began to ease off the gas, unsure of what was happening, I observed what appeared to be a black object quickly shoot upward from the front driver’s side of the vehicle while traveling at highway speed. I immediately took the next exit [XXX] ) to assess the situation. I had no idea what to expect; my mind kept jumping to either hitting road debris or maybe even a blowout. To my astonishment, once I was safely on the side of the road and out of my vehicle, I noticed that the front left fender flare had completely detached from the vehicle suddenly and without warning while cruising at normal highway speeds. The 2023 GMC Sierra 1500 in question had approximately 29,800 miles at the time of this incident. I immediately contacted the dealer to schedule a repair, and all pertinent records, including photographs and a repair invoice, can be made available upon request. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Tailgate opened several times without being prompted. Once while driving, two times while in park.

The tailgate automatically opens when I open the driver door. There is a recall on this for GMC Sierras, same model and year but were manufactured in Canada. This is happening to my vehicle but because it is manufactured in USA it is not part of the current recall. PLEASE recall the USA trucks too. Dangerous!

My GMC was listed under a recall that came out in 4-24-25. This issue can cause loss of propulsion to my vehicle and can cause serious risk of injury or an accident if the issue does occur. I tried to call my local dealer in Auburn WA to address the recall and was told there is no fix as of yet. Because of how serious this issue can be I’m shocked GMC is dragging their feet on a fix. I think this needs to be looked into and expedited to avoid injury.

Gm has acknowledged there is a safety risk to continue driving my truck due to potential engine failure. I was prompted to take it to service to have the issue assesed which I did. The dealer said they would not inspect it because there is no resolution approved. I offered on 45/1/25 to pay them to check it out but they refused. This is dangerous and unacceptable, I hope you can help.

2023 GMC 1500 Sierra Denali Ultimate tailgate opens without being commanded. This has happened approximately three (3 ) times in the last two months while being driven with the most recent incident occurring today, 04/27/2025. There are no warning lights indicating when a tailgate opens while the vehicle is being driven.

The electronic tailgate randomly opens on it's own/fails and opens when it has not been pushed to open. The vehicle is available for inspection. The tailgate opens randomly and can be unknown that it is open. No warning of it at all. It has happened multiple times, the most recent being today 4/7/2025. I know that a recall has happened with other models for this exact same issue.

I was driving at approximately 25-30 MPH, accelerating from a stop light and I felt a clunk, heard a grinding noise and my back wheels locked up. It was snowy/icy conditions so the back end of my pick-up slid out to the right a little bit before the wheels unlocked and I was able to regain control. I could have slid off the road or into another vehicle had the wheels remained locked. The computer system then alerted me to a transmission issue and to reduce speed immediately and call for service. The pickup was then unable to shift out of 1st gear. The vehicle has been towed to a dealer and I have been informed the valve body in the transmission has to be replaced which is 8-12 weeks backorder.

1) [XXX] - Was driving on the interstate at 65 - 70 mph when the truck suddenly shut off and shifted to neutral. I was in the far left lane and had to coast thru 2 lanes of high speed traffic to the right shoulder before the truck stopped coasting. Once I coasted to a stop on the right shoulder of the interstate, I tried to crank the truck up a couple of times and it finally cranked and I proceeded on to my destination. When I reached my destination and was attempting to park, the truck shut off again and would not crank after that. I then called roadside assistance to send a wrecker and take it to my local GMC dealer in Montgomery, Alabama. 2) My safety and others was put at risk when the truck, without warning, shut off and lost power while driving at 65-70 mph in heavy interstate traffic causing the truck to suddenly decrease speed and having to maneuver through traffic , without power, while coasting to the side of the road. 3) [XXX] - The service department at Mullinax GMC in Montgomery, Alabama called me about a week later to say the engine had "LOCKED UP" and that they had contacted GMC to begin the process of getting it fixed. They indicated that this was not uncommon with this model truck, and that it happens sometimes. 4) There were absolutely no warning lamps, messages, sounds or any other symptoms of the problem prior to the engine failure. I was caught completely off guard when the engine shut off. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Complete engine failure while driving on interstate. Vehicle went into neutral. After rolling to a stop on highway. Vehicle would not go into gear. Tow was unable to put vehicle into saftey mode and had to drag vehicle onto tow bed. At dealership techs were also unable to get vehicle to turn on or go into gear. Dealer advised the engine was complete seized. This happened while traveling on the highway there was no warning or signs of something being wrong. Vehicle simply lost all power and went into neutral while traveling 70mph with 37k on the odometer.

Unknown , I don’t know why are your recalls module

This vehicle has an electronic tailgate release mechanism. This is the 1/2 ton version of GMC ‘s pickup. The tailgate releases randomly and opens, generally while driving down the highway. I have dump the contents of the truck bed on the road immediately in front of vehicles which are behind me, causing serious handling and collision issues for the trailing vehicles. No accidents have occurred yet. When I have called the GMC dealer, they inform me that the electronic tailgate release mechanism HAS BEEN RECALLED ON OTHER GMC TRUCKS for this EXACT reason but NOT for my model. While they will repair the device if they can get it to fail in the shop(which it wont), they will NOT replace it under warranty because it has not been recalled. How can this be?? It is clearly a recall issue and should be included in the recall program.

The radiator began leaking due to the fact it was falling out of the vehicle. The bolts holding it in became loose and just fell out. No lights or warnings were displayed on the dash to announce an issue was occurring even though the fluid levels had clearly dropped.

Engine goes to limp mode multiple times 3 of which happened getting onto the highway and almost creating an accident due to the reduced acceleration mode. CODe u0656 00 popped up each time. Dealer has yet to rectify due to lack of appointments… making me keep the vehicle saying it’s drivable but each time randomly goes into the reduced acceleration mode every restart. (Blasius GMC Branford CT)

The bed tailgate will come down on its own. There is no warning or message to indicate the tailgate is down. This has happened at least 6 times in the past 6 months. The dealer is aware and some models have had a recall but I have not gotten one yet. The danger is something coming out of the bed while driving down the road, which happened to me and lost a crate with trailer ball hitch and straps. I don't know if it caused an issue because i don't know when or where it fell out. Googling this shows it is happening a lot. Very dangerous and some sort of correction or warning.

I purchased a 2023 GMC Sierra 1500 Denali trading in the same 2022 version [XXX]. I would find the tailgate down after stopping. It became habit to make sure the tailgate was latched. Unfortunately, while pulling a trailer, the tailgate opened again while driving causing me to have to replace the top portion of the multipro tailgate. The new tailgate would be damaged a second time despite my efforts, but traded it in for the 2023 as it was. This continued but more often with the 2023. Two weeks ago I was pulling my trailer driving from San Diego to Las Vegas and we were flagged down by another car on [XXX], and we realized the tailgate had opened. We were thankful he did because had anything fallen out, we were super concerned it could cause havoc with the traffic that followed. We put a bungy cord on it. The next morning driving the trailer 4 blocks but knowing we would make a u-turn, and a sharp right turn, I opened the tonneau cover so I could clearly see the tailgate, I was pulling the trailer, and I had my eye in the rear view mirror. Lo and behold, the light turned green, I paid attention to traffic, and I made the uturn. I felt the tailgate being crushed. This time, it took out the entire tailgate, and caused moderate damage to what was also crushed on my trailer. The notion that these tailgates are not opening while driving is simply not true. I have experienced this not once, but twice. As if this cannot get worse, GM tells me my truck is not part of this recall. They so far have refused to give me the "fix" for it so I can fix on my own dime. And on top of that, my body shop told me the tailgate replacement is on back order for months with no idea when production for these will catch up. This one will cost $3300, my trailer $800, and the 2022 truck about $2800.00. Besides the obvious cost and aggravation, the bottom line is that it is a safety issue for other drivers. I am concerned. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)

Purchased our truck 3 weeks ago. Driving this morning heard a loud pop then a min a second pop sounded like gun shot. The rear window both sides shattered. We have the rear defrost on. This is a horrible hazard.

This vehicle has a remote tail gate drop function in the center console. The button is extremely easy to accidentally activate and will activate at any time including when in gear. This creates a significant safety risk as the tailgate can accidentally open while driving at high speeds and cause any load or objects in the bed to fall out and become dangerous projectiles and/or significant roadway hazards. In addition there is no warning message to indicate that the tailgate has opened, creating further safety concerns that the vehicle operator would not realize that the tailgate has opened until they start to lose the contents of the bed. There is no vehicle setting that will disable this function, creating a situation where it is impossible for the operator to ever safely secure objects in the bed.

Upon start up the HVAC fan speed reduces by self and will not increase by own in auto mode.

--Unwanted Reduction in The Front HVAC Blower Speed and Loss of Radio, Auto AC not working as designed --driver seat vibrating as the lane departure warning activated; I had turned the seat vibrate function off on 25 June 2023. I then went into settings to turn the function off again, and the system would not allow to make the change, it stayed in vibrate function --the passenger front window will not go up automatically, had to hold the button to make the window go up all the way. I then had a message in the DIC, that said, “Open and close passenger door”. I did so, at the next stop, but the message stayed on the DIC and the window still would not go up automatically with the button -- when the vehicle is operated and the AC is NOT on, just the fan, and windows down, and the auto temp set at 68 degrees, when at idle, there is an obvious increase in very hot air coming from the vents and stays that way until the vehicle is back in motion. Then it seems to adjust back toward normal outside air. During all this operation the recirculation is open to outside air --auto rain sensing windshield wipers; stops at full arc and hesitates during operation --driver side review mirror does not go back to preset 1 position, when put in reverse, both mirrors tilt lower, as I have set, but when put back into drive, the driver mirror does not fully recover until I push the 1 setting --DIC message of key not in vehicle, even when the key is in vehicle and vehicle is in motion, the DIC message stays on screen saying key not in vehicle --with AC in ON position, cold air stops and very warm/hot air starts coming out for about 30-60 seconds, then cold air starts coming out again, happens during driving and stopped, at any speed --Truck WIFI does not connect automatically SOFTWARE NOT UPDATED FROM GM- OTHER SAFETY ITEMS ARE AFFECTED --Auto headlights --Auto brakes --Auto wipers --Auto systems not working as designed

Sunroof glass shattered. This is the first summer for the truck. Travelling at ~75MPH the sunroof glass shattered. Neither driver nor passenger saw any objects in the air. I was not travelling under an overpass. Over the last 2 months I have been awaiting repair I have tried various methods to cover the sunroof and all have failed. Some easily pop off. Others hold better, but when travelling at higher speeds (>50MPH), the covering will bulge outward presumably from the pressure difference from outside to inside the cabin. My guess at root cause is a combination of pressure on the glass created by airflow over the truck at highway speeds, ~85degF air temperature, full sun load, and possibly stress of the roof (which is black).

Bose radio randomly goes to maximum volume and you cant turn if off. This has happened twice and nearly cause wrecks each time trying to get out of traffic to turn the vehicle off.

I sent my vehicle to the dealer, Brandywine GMC dealer in Bradywine MD. To have my fluids topped off upon receipt of my truck the next day my truck broke down. I sent my truck back to the dealer where they said Def was placed into the diesel tank by me, which was a lie. I filed an insurance claim because the dealer accused me of putting Def into my diesel tank. The insurance company paid to have everything fixed, however shortly after receiving my car I was traveling the interstate and my speed was cut back to 15 miles per hour per the trucks computer, which almost caused my vehicle to be rear ended. I took the truck to Alexandria va GMC because the codes were telling me that the injection system default , which Brandywine was supposed to have fixed.