general problems of the 2020 GMC Sierra 1500 - part 1

The brakes suddenly activate and cause the vehicle to rapidly stop with no warning of any kind and without any braking action being taken by the driver. Then, the brakes do not release and the vehicle cannot be moved as the brakes remain on. Turning the engine off and then restarting it or shifting to other gears does not release the brakes. The vehicle remains immobile and cannot be driven. After a few hours have passed, like overnight, the brakes release and the vehicle can started and driven just as if nothing had happened. A message briefly appears on the vehicle information screen each time this inadvertent braking occurs. It reads, “brake failure system”. These brake lockdowns occurred when driving on streets and in the driveway. No accident resulted but could have easily occurred. This is dangerous for a driver and occupants of a vehicle with this safety flaw as well as for other people and vehicles in the vicinity. This has happened five times. The last two instances resulted in the vehicle being loaded onto a tow truck and taken to a dealer of the vehicle’s manufacture. Thus far the dealership has not found what may be causing this intermittent braking problem.

First my torque converter went out, no warning lights only shaking wehn shifting, I got it replaced already it cost me $2400 second warning light service for brakes, traction and power steering come on and off. And sometimes truck doesn't brake well and steering wheel feels hard to drive, it has happened while on expressway with family. Third engine oil low add oil warning sign comes up alot and I have to add oil, engine has a rough idle now, also when I turn truck on smoke comes out while having a rough idle, recently it started knocking, I haven't moved the truck since than.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 45-50 mph, the check engine warning light and the brake warning light illuminated. Additionally, the contact heard an abnormal sound coming from the engine, and the vehicle decelerated. The vehicle was taken to the dealer, where it was diagnosed and determined that all the engine lifters and the camshaft needed to be replaced. The vehicle was repaired. The contact related the failure to NHTSA action number: ea25007 (engine and engine cooling). The manufacturer was notified of the failure and informed the contact that the VIN was not under recall. The manufacturer offered to partially cover the cost of the repair. The failure mileage was 107,787.

On Monday, [xxx], at about 1730 hours was traveling southbound at 45mph on [xxx] approaching the [xxx] intersection. Vehicle alerted to the following codes on the dash; escape, traction control, check engine light, brake system failure, "do not exceed 62 mph". I took foot off accelerator and looked up and noticed the traffic light turning red. I applied pressure to the brake and noticed there was no brake pressure at all, and the vehicle continued to roll forward towards the intersection. I put the truck in low gear to slow and continued to pump the brake rapidly. As the truck gradually slowed I turned truck off until it came to a stop. When I restarted the truck the brake hydraulic pressure returned and only the check engine light remained on. I took the truck to reliable GMC in the roseville automall the next morning. The service department claimed the agm battery was bad and caused the front brake caliper sensor to throw a low voltage code causing a cascade event of codes throughout the system. The loss of my brakes nearly caused me to enter an intersection unwillingly and could have led to a serious accident. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Was driving down the freeway around 65 miles an hour attempted to pass a truck when the steering started wobbling the abs that ems and the breaking system came on with the check engine light almost had no control and barely avoided having an accident the only way it went back to normal was slowing down.

My vehicle displayed numerous brake failure codes and limited my speed to 43mph. When taken into my local GMC dealer the diagnostics I was given were a bad/leaking master cylinder. This vehicle has 16,200 miles on it and was never used for towing or hauling. The brakes are hard and brake assist has clearly failed. I’ve found numerous recalls and issues with other year vehicles from GMC, yet they are denying any liability on my vehicle. They want over $3000 to replace the master cylinder even though there’s no physical leak observed via fluid loss. This is a major safety concern when a major brake component fails on such a low mileage vehicle. This truck also has a well known seal leak on the rear window that causes mold to grow inside of the vehicle cabin. Apparently no one has died yet so they have not been forced to put out a recall. Consumers should not be forced to spend thousands of dollars on major components on such low mileage vehicles. Especially when it comes to safety items like braking. I’ve researched this for hours and have found this has been a known issue on these 2020 models many people. Some even brand new after driving them off the dealership lot. Clearly there is an issue and the manufacturer refuses to address it.

I will start by saying that I have had this issue since I had the truck (2020), less than 10k miles. I mentioned to the dealer multiple times. I was told that they can't figure it out since it has to be doing it while it is at the dealership to figure it out. I am finally fed up with that answer. The issue is with trailering. It will randomly lose trailer brakes while driving down the road. Sometimes the brakes will come back right away, sometimes they will not. Other times other lights that should be working will randomly stop working as well such as turn signals. This has happened multiple times and I only tow a few times a year when I pull my travel trailer. I have a video of it doing it as I am driving down the road. For the additional details with approximate date that this incident occurred, I will put the last date that this was found.

I was driving my 2020 GMC Sierra 1500 on a local street when the dashboard suddenly displayed a “brake failure” warning. I immediately realized I had no braking power and had to safely roll into an uphill parking space to stop the vehicle. While waiting for the tow truck, I researched the issue and discovered there is a known recall related to the brake calipers on some 2020 Sierra 1500 models. However, when I entered my VIN, it showed no open recalls. I also contacted GMC directly, and they confirmed that there are no active recalls associated with my vehicle. Additionally, the vehicle's onboard information system indicated that the front brakes were at 65% and the rear brakes at 80%, suggesting that brake wear was not a contributing factor.

I was driving about 45 mph when the vehicle started to brake on its own. Message center said "brake failure max speed 62 mph". I had to move the vehicle, so I continued forward. It was still trying to self-brake, I decided to stop and turn ignition off so computers could re-set but I had no brakes. I had to stand on brake pedal to get it stopped. Turned ignition off and restarted. The problem was gone, but it happened again 2 weeks later. Took to dealership where purchased and they said it needed a computed recalibration. Something I didn't know about. They charged me $200 to recalibrate the computer. My issue is the danger of not having brakes, not the $200. How many similar vehicles could this happen to?.

Recently when starting truck brake message alert comes across on dash reading brake error, and not to drive above 45 miles per hour and brakes are not totally operational, meaning brake pedal has alot of play in it to bring truck to a stop. Have to turn off vehicle , sometimes repeatedly before it apparently resets computer system. This has now occurred four times in last five months. Events and dash warning message very similar to recall issued 3/3/20, but listed as "complete" on recall data base. Need to seriously and immediately looked into and corrected!.

Vehicle shifting poorly, and I have had a bunch of brake and rotor issues.

-transmission valve body failure, wheel lock up, abs event, loud bang and a flashing "d" on driver information center (dic) when lightly or moderately accelerating forcing an 8-7 or 8-6 downshift -when all four tires lock up at a high rate of speed, this puts the driver, the passengers, and all others on the road at risk for injury or death. -yes, the problem has been found in a document by my local dealer that this issue was added to my exact vehicle's service manual on 11/27/24. The document describes in detail the exact scenario I have been involved in multiple times. It is deemed as #21-na-275. It locks up the tires randomly to the vehicle in mid acceleration at any speed including 80 miles per hour in one instance for me. -yes, the dealership inspected it and found the issue to correlate with the newly added section to the service manual, 13333166. This document id is 5925530 and the added information to the dealership is #21-na-275. The GMC manufacturer has been contacted as of 3pm mst 3/14/25. Insurance doesn't deal with mechanical problems. The police will only be involved when there is death or injury. -no. The only warning that happens is simultaneously as the vehicle locks up the tires causing the driver (me) to inevitably try to save myself and others, swerving and trying to focus on not hurting myself or others but I did notice the "d" flash on one of these occasions. This is the most dangerous issue with a vehicle I have ever even considered. At any time, for any reason, all four tires can lock up at any rate of speed and cause multiple casualties. The way to fix this is to spend $3,000 which I am sure many people like myself do not have. This means there are thousands of these exact make and models of vehicles on the road right now. Please do not take this lightly as I have almost crashed multiple times with people in my vehicle due to no fault of my own.

Brake monitor repair keeps illuminating since 2/1/2025! replaced all brakes and rotors, yesterday 4/27/2025. Now don't drive over 43 mph illuminates, emergency brake illuminates says push brake peddle to disengage parking brake yet parking brake has never been engaged.

My pickup was specifically purchased to pull a duel axle trailer ( brakes required by FL. Law). The trailer weights more than the pick up. They stopped working with the electric /hydrolic trailer brake system. I have had the sierra in three times for warren ty repair. They never fixed the system. I have thoroughly test the trailer system - it works fine with another pickup. Dealer won’t return my calls. Multiple trips taking it in for this problem. Have a case filed with gm. All just placating me, now ignoring my problem. I am stuck and they are not acting in good faith.

The contact owns a 2020 GMC Sierra 1500. The contact stated that on several occasions while the vehicle was started, the check engine, brake system, and another unknown warning light illuminated. Additionally, the messages brake system failure, steering wheel failure, low oil, and two other unknown messages were displayed. The contact also stated that the rear-view camera remained displayed while shifted into drive, and the instrument panel failed to operate as intended. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 65,000.

My brakes failed 2 times. One time I almost got into a horrible wreck with my daughter in the truck. "brake system failure" " max speed 43mph" I have not had any brake work or anything done. The dealer is trying to charge me to replace the whole brake system when [xxx] this says to reprogram. Still waiting on GMC to tell me if it's covered under warranty. From my own research this has been a major problem for hundreds of people if not more. I could have died because of a faulty brake system or a bad software update. I need help with this and so do the countless other 2020 gm owners. There is a recall on the 2019 for the exact problem but not the 2020s. Gm safety recall n192268090 please advise information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

My truck 2020 GMC Sierra 1500 at4 denali is not working properly since July 2024. I took it to 2 different dealership to get a diagnostic and I finally ended doing the repairs for brake issues. I have been towed 6 or more times and almost experienced 2 car accidents since I drive the truck after the supposedly repairs where done but I ended stranded again with no brakes. The dealership has repair the truck 3 times but im still getting sevaral codes the fact that I had to pay out of pocket and have to deal with this and expose myself to danger and my family in driving a vehicle that is no safety condition its absurd. I call several times the recall gm hotline and I was told GMC 1500 are included in the recalls just not the at4 and I have a family member with the same truck and same issues she ended up trading in the truck recently since she kept experiencing the same issues over and over again just like me.

The contact owns a 2020 GMC Sierra 1500. The contact stated that the vehicle failed to start. The battery was replaced, and the failure was remedied. On another occasion, the contact stated that the brake percentage was low on the instrument panel and that the lights were becoming dim. The vehicle was taken to a dealer where the brakes were replaced; however, the computer failed to detect the repair; and the message "1 more mile left to drive" was displayed. The contact also stated that two weeks later while driving 45 mph, the brake pedal failed to respond and felt abnormally loose. The vehicle was driven over a concrete sidewalk to stop the vehicle. There was no crash, and no injuries were sustained. The vehicle was towed to the residence. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and confirmed that the VIN was not under recall. The approximate failure mileage was 102,000.

Lost break, second time this month, showing break failed 40 mph max speed, abs light on, break light on, and 2 more light on the car with antislipiring or something like that, the another one no idea what it is.

The contact owns a 2020 GMC Sierra 1500. The contact stated while driving 60 mph, the service brake, check engine, and abs warning lights were illuminated. The contact took the vehicle to an independent mechanic to be diagnosed and it was determined that the passenger’s side rear caliper needed to be replaced. The vehicle was not repaired. The vehicle was taken to the local dealer to be diagnosed, and the contact was informed that the rear passenger’s side caliper needed to be replaced. The vehicle was not repaired due to the parts not being available. Upon investigation, the contact associated the failure with NHTSA campaign number: 20v116000 (service brakes, hydraulic) however, the VIN was not included. The manufacturer had been informed of the failure. The failure mileage was approximately 69,000.

We were hauling a trailer and driving approximately 65-70mph with cruise control enabled. The vehicle randomly disengaged cruise and the abs telltale illuminated, lost brake functionality completely. Safety of my family and other vehicles around us was compromised! downshifted to try and navigate the vehicle to the side of the road and the esc warning text came on the screen. Was able to luckily stop vehicle by downshifting. Turned off ignition and then cycled back to run, brakes and all warnings were cleared. Started driving vehicle with flashers on the side of the road see what would happen and approximately ten miles later same thing happened but this time brake functionality was reduced significantly but not completely but still had to downshift to stop. Called GMC and was told this was not a recall even though vehicle brakes randomly stopped working. Told us they would do nothing since the vehicle was out of warranty 80k miles and warranty was 60k and also since no one was hurt. We were 1-2 hours from being in the mountains driving and not sure we would be here today if this had happened in the mountains! dealership ordered a new master brake booster and abs. When installed the part would not flash and gm engineering told them to replace the part a second time. They we’re told to keep flashing till it takes even though the second module was also bricked. Seems strange a new part would be broken as well and the master cylinder was resetting. Dealership states the vehicle is fixed but the safety of my family and others driving around me were in extreme danger when this happened. Do not feel safe driving this vehicle and not convinced this will not happen again. When we called gm they told us they are receiving many calls about this happening to at4 vehicles but they have not issued a recall yet. Submitting this because vehicles should not randomly lose brake functionality and do not want others at risk or my family.

Normal driving conditions vehicle decelerated and warning lights and notification appeared. Warning were ‘service ecs’ and ‘steering assist is reduced drive with care’. Shut off vehicle for 30 minutes and warnings were no longer present and vehicle drove normally. Happened again 24 hours later. Received email notifications from GMC to arrive within one day. This was a know recall of the previous model year.

I was stopped at a red light and when the light turned green I accelerated and the vehicle shut off and then came back on. When the vehicle came on I had a service esc light and a system break failure warning telling me not to exceed 62mph. I made it back to my house driving with extreme caution. The breaks were very delayed while driving.

Brake pad monitoring system alert came on driver information center warning screen. Brought to local dealer who told me I needed new brake pads. There is a current safety bulletin on the NHTSA. Gov website for the 2019 model year GMC sierra, as well as the 2019 Cadillac ct6, but not he 2020 model year. The week prior my driver information center reported front brakes in the high 80's and the rears in the low 90's in terms of percentage of brake life remaining. How can the system go from being safe to being unsafe in a week (and less than 200 miles)? at this point I don't know if my vehicle has a safety problem with my brakes or if there is a sensor and programming issue as described in recall n192264451. I have no observable issues while braking - no pulsing, noise, chattering - that would indicate any brake problems. My only inclination is the alert on the driver information center. Both local dealer and gm customer service are telling me to perform service and pay out of my pocket. This seems inconsistent based on the above recall.

The truck stated to have the check engine light on, by the time that happened the brakes were hard to step on it and the steering wheel hard to turn, I had been asking to GMC superior of siloam springs to check the truck because, got scared while I couldn't make stop the truck while on traffic, but they don't had open appointments for that day or the other following days, so a week after they got one and I missed because my work, I set another one at GMC on springdale but they want me to charge me whenever the truck has an extended warranty, so I told them to leave it like that so finally got another appointment at siloam springs location but while driving down there the same thing happened all the light on warning messages on the dash board start showing up and the brakes were hard to step on it and the steering wheel hard to turn, I got told them what was happening, about and how exactly happened. That day after 30 minutes I got a call saying that it was fixed I still asked if they were sure he said yes, the next day I almost crashed with a neighbor at my work place because I couldn't stop the truck, so today I took back the truck and the guy at the desk told me that they may just erase the codes and don't really checked what was wrong, I'm just filling this report because even if I got full coverage on that truck, I'm not gonna be responsible if I'm involved in an accident.

I own a 2020 GMC Sierra 1500 4-cyl, turbo, 2. 7 liter with 20k miles and I owned the truck for almost 2 years. All of a sudden my vehicle started receiving multiple warning messages. While driving I stopped, and when traffic stopped in front of me the engine died all the lights were on warning messages on the dashboard started showing up. Electronic stability control, antilock braking system, ecm, reduced engine power, etc. , and the brakes were hard to step on it and the steering wheel hard to turn,I took my foot off the brakes and pressed it again to start. It started but the check engine light was still on, this happened four times already and three times while parked when I tried to start, after a few tries giving few minutes intervals, it will start with all the lights on and warning messages on the dashboard start showing up. Electronic stability control, antilock braking system, ecm, reduced engine power, etc. , and the brakes were hard to step on it and the steering wheel hard to turn.

Own a 2020 GMC sierra at4 with 13k miles and I owned the truck for 1 year. All of a sudden my vehicle started receiving multiple warning messages. Electronic stability control, antilock braking system, ecm, reduced engine power, etc. I see there was a recall for 2019 GMC sierra's for the same issues. Why isn't 2020 GMC sierra's not also part of that recall ? it is ridiculous that a brand new truck has these types of serious issues affecting so many vehicles. Why is GMC allowed to continue to sell later model trucks after the 2019 recall with the exact same esc and anti-lock braking system problems ?.

Two times while on the freeway the service parking brake and engine lights came on and starting braking. Could not drive over 20 mile an hour. Both times taking to dealer the lights where not on and they could not find anything wrong. I even have video of it happening.

This vehicle was involved in a fatal crash when it rear ended an SUV stopped at a red traffic light. The driver alleges mechanical failure of the brakes. Police performed a vehicle download which captured 5 seconds of pre-accident data. The download shows the accelerator pedal was fixed at exactly 57% the entire 5 seconds pre-crash while the driver simultaneously applies the brakes the entire 5 seconds. A city bus captured the crash on a dash camera. Despite the driver desperately applying the brakes, the vehicle's speed continued to increase and the driver was unable to avoid the collision, and burst into flames upon impact. The vehicle mileage is less than 2,500.

I purchased the 2020 Sierra 1500 because the label on the truck frame states that it can tow 9300lbs. Subsequently, in April 2021, I purchased a 34' travel trailer with a max capacity of 8995lbs. In August, I received a notice from GMC that they overstated the towing capacity by 500lbs. The new towing capacity is 8800lbs. GMC's response to my request for a refund was that they were not going to help me. Their solution is that I can be provided a new sticker by the dealer upon request. This does not resolve my issue, nor the issue of other sierra owners who purchased this vehicle because of its stated towing capacity. In doing research, it appears that in model year 2014, GMC faced a class action lawsuit for misrepresenting their capabilities. I believe that this malpractice is a safety concern for me and many others. Attached is the towing label on the frame and the letter from gm.

On Saturday, may 22, 2021, my wife was returning from fairgrounds in waxahachie, TX. She remote-started the car, and the vehicle started. As it started to rain and was getting muddy, and the grounds are in a grass field (no large rocks, hills or debris to climb as it's cleared land), she shifted the vehicle into 4wd high incase the field was slick. She started to drive and received several warning lights, "service esc, service traction control, brake light warning and check engine light". The vehicle also had a noticeable wobble to the wheel and felt off balance, jerky, and had speed limited. My wife turned the vehicle off and back on and some of the lights went off, and the vehicle did not lurch or wobble anymore. The vehicle had a tire changed at the dealer the day prior, so I am unsure if that tire change is related or not. Now the vehicle shows an alert "check engine, service emissions system". I am having the vehicle towed to the dealership tomorrow for diagnostics. All lights except the check engine light have since turned off since powering off the vehicle.

My truck Tuesday March 16th had me update software as soon as I got to work, after it was done I got out of my truck and it would not lock with push button or fob. When I got into my truck to go home 10hrs later it made a bunch of clicking noises and after a minute it showed update complete on screen then started. The very next day I drove back to work which is 22 miles. When I took my truck to lunch three blocks away I had esc service light and service parking brake accompanied by check engine light. I called local dealership to get it looked at and they said Friday was as early as I could get it in. I left work early at 1:30 and tried to drive it and it was squalene like a bad power steering pump and shaking as I drove. I went ahead and took it the dealer.

Car was idling and parked. Warning code showed up on dashboard esc, electronic stability control, reduced engine power. Vehicle then displayed transmission disruption, warning light displayed as well. I was able to drive it to the dealership but the performance of the vehicle was limited by the reduced engine power. Transmission was hesitating and clunky during gear changes. My sierra has 5,000 miles on it and the transmission was already replaced at 2,000 miles. GMC has a serious problem with this make and model. Unsure what the resolution will be, but I am no longer confident in the product GMC is selling.

Brakes have been squealing since 4000 mile mark. Dealer states it’s normal.

Dear NHTSA, I am filing a complaint against general motors, llc (gm) for failing to follow through on a legally binding lemon law settlement and leaving me with an inoperable, unsafe vehicle. Vehicle information: •vehicle: 2020 GMC Sierra 1500 •VIN: 3gt1p8bed4lg424389 •date of purchase: October 1, 2020 •dealership: diamond Chevrolet Buick GMC nature of the complaint: 1. Vehicle declared a lemon: •gm acknowledged that my vehicle was defective and offered a ccp § 998 settlement on April 18, 2024, for $97,000 plus pre-judgment interest. •despite accepting the offer, gm has failed to facilitate the buyback or repurchase of the vehicle. 2. Ongoing safety hazard: •the vehicle is non-operational and poses a safety hazard due to repeated transmission failures, loss of engine power, steering/braking issues, and limp mode activation. •gm’s delay in replacing the vehicle leaves me exposed to ongoing safety concerns. Request for action: I request that the NHTSA: •investigate gm’s failure to address and rectify the vehicle’s safety issues. •document gm’s negligence in resolving safety defects under a recognized lemon law claim. •initiate necessary action to protect consumers from ongoing safety hazards caused by gm’s failure to act. Please contact me for additional information or supporting documentation.