2020 GMC Terrain Complaint Log

During a vehicle accident, my 2.5 year old daughter's car seat detached from the base and landed in the back part of my part. We were t-boned on the passenger side back seat. We spun and the car seat detached and she was flung around the car. She had severe whiplash, a contusion and possible fabric burn on her head. She was buckled in properly and the car seat was properly installed. Yes, all parties (other than manufacturer) saw and inspected the car seat.

The contact owns a 2020 GMC Terrain. The contact stated while driving 45 MPH, the vehicle inadvertently lost motive power. The contact was able to pull over to the shoulder of the roadway, where the vehicle failed to restart. The check engine warning light was illuminated. The vehicle was towed to the dealer, who determined that the engine had seized. The contact was informed that the engine needed to be replaced. The vehicle was repaired, but the failure reoccurred. The vehicle was again towed to the dealer, who again diagnosed a failure with the engine. The vehicle was not repaired. After investigating the failure, the contact related the failure to NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); but the VIN was not included. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline for assistance. The failure mileage was unknown.

[XXX] once again while diving down the road 45mph Terrain once again goes in to park ,I was lucky the lady behind me wasn't to close .Also I contacted onstar when I was able to get vehicle moving at the store ..I told her what happen she ran diagnostics while parked at store said there was no codes I let onstar know this has happened several times..I had no warning, no indication, no lights came on.And I also let her know that this same vehicle was still stalling I was at intersection and the auto/stop is always on it will not let you bypass or default took it to dealership who I bought CPO back when it first would not let me turn it off cause its stalls at stop signs ,red lights etc crazy thing is if you turn the ac on it cranks up , if you hit the door unlock it starts... Thats not normal GMC knows that the dealership whom sold me CPO that wasn't the misleading is beyond crazy..GSM cussed me out It comes with life time warranty but when I had it towed right after I bought it 2 months ..I was talking about what the mechanics had said that this vehicle was in prior flood and accident GMC onstar has a different Vin then the one that on the vehicle..The doors are not original I can see the inside of steering wheel and on dash where they said air bags were deployed and they did a [XXX] job hiding it ... I paid over 32k for this 2020 Terrain that was advertised as CPO with 1 owner in Florida they showed me a fraudulent carfax, I pulled up my own and it came from New York ..This vehicle is not safe to drive but I dont have any other options..I have made complaint with both GMC and my finance company whom also wrote complaint on dealership and the told me I could rewind the loan but when I told dealership I knew that they sold me a vehicle that was not CPO and what I learned He came at me at dealership infront of workers and customers .. The vehicle just going to end up getting myself killed or someone else.. Semi had to run off road to avoid hitting me INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Having problems with fuel system

Vehicle stalled while stopped in middle lane during rush hour traffic. Vehicle would not start, and could not be put in neutral to be pushed to side of road. Vehicle was towed to repair shop where they needed to replace the fuel pump control module. The automotive repairmen stated they have seen this with multiple GMC vehicles and they do not understand how it has not been recalled yet because, as they stated, it is going to get someone killed one day.

SERVICE BRAKE ASSIST CAME ON, CHECK ENGINE LIGHT CAME ON AND VEHICLE WAS HARD TO STOP. Took to authorized service dealer and all parts were replaced. After driving it for a little while, SERVICE BRAKE ASSIST BACK ON, CHECK ENGINE LIGHT BACK ON AND VEHILCE IS HARD TO STOP.

The contact owns a 2020 GMC Terrain. The contact stated that while driving at slow speeds in a parking area and attempting to stop, the brake pedal failed to depress all the way to the floorboard and was firm, requiring an increased effort; however, the vehicle failed to stop as intended. The contact was able to bring the vehicle to a complete stop by turning the vehicle off. No warning lights were illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the brake vacuum pump, observing that the pump had sent metal fragments into the engine, resulting in damages to the engine. The vehicle was not repaired. After investigating the failure, the contact related the failure to Special Coverage Adjustment: N182202780. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 108,000. The VIN was not available.

The contact owns a 2020 GMC Terrain. The contact stated that after starting the vehicle and shifting into reverse(R); the rear-view camera screen was not functioning as needed. There was no warning light illuminated. The message "Service Rear Camera System" was displayed. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 53,500.

Brakes stopped working while driving. Yes it has been reproduced by mechanic. No it has not been inspected by manufacturer. “Service Brake Assist” message populated after failure.

The contact owns a 2020 GMC Terrain. The contact stated while reversing, the rearview camera screen displayed a blue image. There was no warning light illuminated. The dealer was notified of the failure and informed the contact that a fee would be charged for a diagnostic test. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline. The failure mileage was approximately 104,000.

The contact owns a 2020 GMC Terrain. The contact stated that the vehicle failed to stop while driving 55 MPH while depressing the brake pedal. The contact pressed the button that immediately shifted the transmission to park, and the vehicle came to a stop. The contact drove the vehicle to a safe parking space. After safely parking the vehicle off-road, the check engine and brake assist warning lights illuminated. The vehicle was towed to the dealer who diagnosed that the brake booster pump and camshaft had fractured and detached from the vehicle. The contact was informed that the brake booster, vacuum pump, and camshaft needed to be replaced. The vehicle was not repaired because the dealer was awaiting the parts to repair the vehicle. The manufacturer was not informed of the failure. The failure mileage was 101,700.

my vacuum pump went out. my brakes went out at 86k miles. very pour design.

This message concerns a persistent engine light that activates and generates engine code P0299, indicating an engine underboost issue. There have been several occasions where I am driving over 55mph on the highway and my 2020 Terrain SLT fails to pick up speed over 60mph in traffic. I took it to my GMC dealer earlier this year for them to diagnose, and they discovered that the charge air cooler tube had collected moisture. Once that was fixed, the vehicle was fine for about a month when the same thing happened. I took it to another GMC dealer and found that the turbocharger wastegate actuator had to be replaced. Once replaced, I had no problems until it began to get cold where I live. Now the vehicle is doing the same thing. Now what happens is the engine light will come on and give the engine underboost message but goes away after a week of driving. I have taken it to 2 dealers for diagnosis, only for the engine light to disappear before they can figure out what the problem is now. This continues to be an issue, as I frequently drive on the highway over 55mph for work, errands, etc., and presents a potential hazard if I have to pick up speed and can't on a major highway.

No warning, the brake pedal went stiff as a board. No brakes could not stop doing 35 on a residential road. Had to coast to a stop in neutral.

My 2020 GMC Terrain (under 100K miles) was running great until one day, after starting the vehicle, I shifted into reverse and felt soft brakes before the engine suddenly shut off. A licensed mechanic diagnosed the issue, pointing to Technical Service Bulletin #PIP5835, which identifies a defective brake vacuum pump. This failure caused damage to the exhaust camshaft and timing belt, ultimately leading to the recommendation of a full engine replacement. GMC’s response? They advised me to pay for their diagnostics and repairs, then file for a "Goodwill Repair," which they admitted was unlikely to be approved. Meanwhile, GM has since replaced this defective vacuum pump with an electric version, acknowledging the flaw—yet leaving owners like me to cover the cost. I believe GM should stand behind their product and take responsibility for this engineering failure, instead of forcing customers to absorb the expense.

The brake system failed. No warning. When the brakes failed, driver ran the car into a tree to stop instead of hitting pedestrians or other vehicles

The contact owns a 2020 GMC Terrain. The contact stated while driving 20 MPH, while attempting to slow down, the brake pedal was depressed; however, the brake pedal felt abnormally stiff. In addition, the vehicle hesitated to come to a complete stop. The contact became aware that the driver's side and passenger’s side struts had failed. The check engine warning light was illuminated. The vehicle was taken to the dealer where it was diagnosed that the brake vacuum pump needed to be replaced. The brake vacuum pump was replaced, and the vehicle was repaired. The manufacturer was notified of the failure and referred the contact to the dealer for assistance. The approximate failure mileage was 17,361.

My car sunroof drainage system is not draining properly and GMC won’t see me for a month. There’s an excessive amount of water that’s pooling in the rear passenger floorboards buckets of water.

Vehicle has not recently been inspected, backup camera has recently gone out leaving only a blue screen with "service rear vision system" to my knowledge nothing has happened to the unit that would cause this. Regular day to day driving, there was nothing that would have given me any notice that this would be happening.

The contact owns a 2020 GMC Terrain. The contact stated that the vehicle was taken to a dealer for an oil change. The contact stated that approximately 5 weeks after returning the oil change, while driving at approximately 65 MPH, the vehicle and steering wheel started shaking abnormally and the vehicle lost motive power. The contact stated that the traction control, check engine, and stabili-trak control warning lights were illuminated. The vehicle was taken to a dealer where it was diagnosed that there was no oil in the engine and the spark plugs and ignition coils needed to be replaced. The vehicle was repaired; however, the failure reoccurred three weeks later. The manufacturer was not notified of the failure. The failure mileage was approximately 37,000.

The contact owns a 2020 GMC Terrain. The contact stated that while his wife was driving 5 MPH and exiting a parking lot, the vehicle inadvertently stalled. There was no warning light illuminated. The vehicle failed to restart. The messages "Low Battery" and "Start the Vehicle" were displayed. The contact stated that the brakes had seized. The vehicle was towed to the dealer, where it was diagnosed and determined that the fuel pump and the fuel pump driver control module needed to be replaced. The vehicle was being repaired. The manufacturer was notified of the failure and informed the contact that the vehicle was not covered under warranty. The failure mileage was 45,175.

My Terrain has a light that has been coming on for a couple months. Service Brake Assist. I took it to the dealer after my brakes locked up and about $800 after getting it fixed the light continues to come on. The forward collision light comes on every time I start the car. More the check engine light came on and says engine electrical system. What the heck is going on? I love this car and take very good care of it but I feel like the $800 that I just spent was a waste. I fear that I will get in a wreck like when the brakes totally locked up and I couldn't press on them.

The engine in my 2020 GMC Terrain is consuming oil at an alarming rate, burning through a full supply within one hour of operation. This excessive oil consumption has repeatedly caused significant damage to the coils and spark plugs, rendering them ineffective within 24 hours. The issue has led to multiple cylinder misfires, poor vehicle performance, and a transmission stall, posing a serious safety risk while driving. The GMC mechanic at Jim Ellis Buick GMC diagnosed the problem as internal damage to the pistons, which they state requires a full engine replacement. They also confirmed an internal oil leak within the engine, which is contributing to bad emissions and further degrading vehicle performance. This defect not only compromises the reliability and safety of the vehicle but also raises significant environmental concerns due to the excessive oil burning and emissions. I am requesting a thorough investigation to address this issue and determine whether it is part of a broader manufacturing defect affecting similar vehicles.

The contact owns a 2020 GMC Terrain. The contact stated while in reverse(R), the back over prevention camera displayed a blue image on the screen. The dealer was notified of the failure but offered no assistance. The manufacturer was also notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The vehicle was not repaired. The failure mileage was approximately 58,000.

Slowed down from coming off of the highway to turn into the gas station and couldn't slow down. The brakes FAILED. Was trying to pump them and was able to come to a forecful stop, nearly colliding with the car in front of me and then again at the gas pump. Car had a failed vacuum pump at 65,000 miles. If this happened during normal rush our, my kids and I would have been sandwiched between two cars. Fatal flaw that clearly GMC already knows about. The Terrain should be included in the recall.

Gear selector

GMC techs have already documented this issue could not be caused by wear and tear or lack of service - of which there is none the car has been serviced every10k miles as advised. GMC coperate has been contacted case # 71853883 The vacuum pump has failed due to MECHANICAL FAILURE causing it to explode and send pieces into the camshaft. The lack of vacuum caused complete brake failure rendering the car unsafe. GMC is aware of the issue as others habe reported it (I have proof of this) and refuses to recall the cars. The cars loose breaking in the middle of driving with no indicator lights or any other indications. The breaks had just been replaced in may - the incident occurred in October. Has not been driven since.

In September 2024 i was driving down the freeway and my car shuttered like the transmission was slipping. I then proceeded to get over into the right hand lane incase i needed to pull over thankfully, because then i lost use of my breaks, and then my ability to accelerate and steer. Then my car just shut off and would not stop. My vacuum pump just broke with no warning, it has been replaced and my car still won't start, it's going on 5 months now and they still can't figure out why.

Car was very well maintained 2020 GMC Terrain, no warnings prior to the issues. Car started shaking while driving, would not allow me to accelerate without chugging, multiple lights came on including flashing check engine light. Somehow the whole motor and engine needs replaced.

The contact owns a 2020 GMC Terrain. The contact stated that while his daughter was driving at an undisclosed speed, an unknown warning light displayed on the instrument panel. The vehicle started losing motive power and the vehicle shut off while in a parking lot. The contact was notified of the failure and a tow truck was contacted. While waiting for the tow truck to arrive, the contact's daughter was able to restart the vehicle and drive to the residence. The dealer was notified of the failure the following day and the vehicle was towed to the dealer. The contact stated that a diagnostic test was performed, and the contact was informed that metal shavings were found inside the engine and the vehicle was diagnosed with engine failure. The manufacturer was notified of the failure but offered no assistance. The contact was referred to the NHTSA Hotline to report the failure. The vehicle was not repaired. The failure mileage was approximately 67,000.

Back up camera does not work. It shows a blue screen and says service repair needed.

The vehicle is a 2020 and should not already be having electrical issues. The vehicle repair is over 5k for needing a starter motor, water pump and drive belt. A starter should last up to 100k miles and water pump should last 10 years not 4. This vehicle is a lemon and should not have so many issues.

While driving I had to push the brake to the floor and a light came on saying reduced engine power. I pulled over right away and had my car towed to mechanic. The vacuum brake pump exposed and parts went into the engine. The mechanic got all the parts out but now engine has low compression and needs a new timing chain. This is over $3,000 so far. Gm recalled other vehicles with the exact same pump ? Why not the terrain.

While driving reduce engine power light came on and the brakes gave out. I weigh 250 lbs and took all my strength to get brakes to stop car. I tow it and mechanic showed me vacuum brake pump blew up and went into engine. He replaced that and timing chain but still needed work. Towed it to dealer and it needs a new engine $11 000. The dealer informed me they see this alot. ! Why has GM recalled some on the vehicles that has this pump but not the terrain. This is dangerous. If my daughter was driving she couldn't stop this car. It's now junk.

Incident happened August 9, 2020. Brakes suddenly stiffened and unable to stop vehicle. There were no warning signs or indicators. Thank goodness I was going at a lower speed and was able to coast into an area to stop. Ended up being the vacuum pump. This needs to be recalled ASAP. This could have been a fatal accident. I have kept the old vacuum pump as well as the pieces that were thrown from it that the mechanic had to dig out.

Every time it rains, the floorboard of my car is soaking wet. I took it to the dealership, and they stated the leak is coming from inside the firewall. I have only had this vehicle for 2 years and just recently moved to a house without a garage. Now that I am just now noticing it, I am wondering if it was like this when I bought it, but I am only noticing it now that I do not have a garage. They want to charge me over $1,000 just to take apart the dashboard to find the leak and that is just insane. There is no telling how much mold, rust, etc. could be in my car from this leak.

The vacuum pump locked up and sheered off the end of the cam shaft and made the cam skip timing and destroyed the motor. While driving no check engine likes till after i lost power. Luckly i was able to roll to a stop The pumps have been a problem the car is only 4yrs old and has 71000 miles.

As I was driving, brakes became very hard to press. I was barely able to slow down to bring the car to a complete stop. Brakes became very stiff and required a ton of force to come to a complete stop. This came with no warning signs or alerts from vehicle. It was only after this occurred that the Service Break Assist light came on.

The rear backup camera in my 2020 GMC Terrain failed. I first noticed and noted that the image was 'cloudy' on 5/3/2023, and it became very bad by 1/22/2024. On 7/1/2024, the image stopped working completely, replaced with a blue screen on the dashboard screen. I ordered a new camera and replaced it myself on 8/1/2024. Because the dealership did not mention any safety effects or recalls, and instead quoted me a very expensive repair estimate, and the vehicle was out of its 3 year warranty, I assumed it was my responsibility to repair this feature. However, I have seen recent news articles where other vehicles have been recalled by NHTSA for similar problems with backup cameras.

On Wednesday, June 26, 2024 my 2020 gmc terrain unexpectedly malfunctioned and failed to restart. The engine light came on and I attempted to restart it for nearly 2 hours with no success. Fortunately, it finally started and once I got it home my fiancé plugged the car up to the code reader. P129F “Manufacturer Control” were the results. After further researching, this is for the fuel pump/fuel pump control modular assembly. In January 2023, NHTSA released a notice for my exact vehicle for this very scenario I experienced. And as of June 6th, 2024 a class action lawsuit was filed against gmc for this issue as well. My vehicle is not able to be repaired due to 1) my vin not being included on the recall list and 2) all the parts that were in inventory are also deemed unsafe due to the lawsuit documents shared online and this has caused a nationwide back order per my conversation with 3 gmc/chevy dealerships. At this point my vehicle is unreliable and unsafe to transport myself or my children.

The contact owns a 2020 GMC Terrain. The contact stated while driving 40 MPH the "Brake Assist" warning light illuminated. The contact attempted to depress the brake pedal, but the pedal was stiff. The contact was unable to depress the pedal. The vehicle was taken to a local dealer and unknown repairs were performed. The vehicle was repaired; however, recently the failure reoccurred. The contact stated that the "Brake Assist" warning light illuminated, and the brake pedal was difficult to depress. The vehicle was not taken to a dealer or an independent mechanic to be diagnosed or repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 162,000.

While driving my vehicle, check engine light came on. Then, my car proceeded to flash about 4 warnings on the dash, Fuel Level Low (had half tank of gas), Engine Power Reduced, Service ESC, and Service Transmission. My vehicle shut itself off while driving 55 down a main highway and put itself into park. Forcing me to pull over and be stranded on the side of the road. In the way of other cars, with no way to get out of the way. I then had to shut car off, wait, and start it back it up. However, after the first time this happened, I cannot drive my vehicle more than 15 to 20 minutes without it doing this to me over and over again. To make matters worse, I am 37 weeks pregnant, and the last thing I need is to be without a car. I also had just gotten my vehicle inspected and an oil change the week before, with no issues to show. The only thing I did to my car before it did this, was remote start my vehicle, which I do every single morning and have for the little over a year I've owned this car. Also, my car has less than 60,000 miles on it!! The mechanic who is currently working on fixing this issue for me, has concluded it to be a throttle body, or the actuator of the car.

This Saturday morning driving my family to Bradenton as I was coming off the hwy to my exit when I experienced a brake fail I thought, brakes got real hard and I couldn't stop the car on time like I wanted to, so I had to press the brakes pedal harder to come to a complete stop, three different places no one knew what could be the problem until I took it to GMC dealership they can only give a code P0556 / U0401 SERVICE BRAKE ASSIST, seems it was too late to checked out they where about to close , something to do with the busters not sure yet but it's getting checked out tomorrow morning, I was driving on cruise control at a speed limit when this happened, will let you know what's the result of my situation.

Brake booster failed with no warning. Brake pad was hard to push down as I exited the freeway. I came close to hitting the vehicle in front of me which would have resulted in a bad car accident. There were no warning. This is extremely dangerous and is a risk to not only the driver but also to vehicles in the path of a vehicle that cannot stop. This needs to be a recall along with the other vehicles that have a recall for this part.

Heard a ticking noise coming from the engine compartment. I opened the hood to investigate which I first check oil level as sounded like a lifter making the noise but all fluid levels was normal. I drove home and 3 miles later ticking noise went away and my adaptive brake assist came in and the brake pedal was hard to press. Luckily I lived another mile down the road so I got the car home and safely parked it. One of the symptoms is hearing a ticking noise from engine when a braking component fails. Further learned could be a vacuum issue which needs a software update which makes no sense. Had I been traveling highway speeds when this happened this story could have a had a very different tragic ending. Car has less then 53000 miles on it

Purchased Vehicle brand new- Beck & Masten Buick GM - Houston, TX [XXX] Performed rout maint regularly. Last oil change 1-5-2024 before catastrophic failure and complete engine seizure. Towed to Wiesner GMC [XXX] 1-12-2024: Mileage on car roughly 99K- had no issues no check engine light, no mechanical failure or indication that anything was running other than normal. No Start on [XXX] PM after work, tried to return next day with battery , changed out battery, engine still would not start, after new battery installed and we attempted to start, that is when engine started making loud shaking motion while attempting to start, windshield wipers came on randomly. First initial diagnostic: Found all oils & fluids in check, could not identify cause of failure, would have to break down and take apart. Had to authorize the tear down at a 1800.00 cost, 2/2/2024: Broke down engine, found that the crankshaft would move one way , but not other, removed the engine from transmission and now crankshaft moves freely. Now the AC comp is locked up (excessive play on magnet & clutch) , tech still unable to identify what caused the failure, they advised that they found traces of metal in oil pan, scored cylinder walls, starter shorted as well. They still could not indicate where these metal pieces came from, how or that it was due to owner negligence or manuf defects. Again this is a vehicle with 99K Miles and now we were looking at a 15K price tag for a new engine, turbo, AC, starter on a car that is worth 12K. This is absolutely insane. We reached out for Goodwill Discounts for some assistance since the dealership could not solidify a cause of failure, but GM decided to not warranty and stand behind their product. We were left with a rebuild option for 7500.00. which we had to do in order to get the car back. I am completely disappointed in GM as a company. This engine should have never failed at 99K. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2020 GMC Terrain. The contact stated that while at a stop, there was an abnormal burning odor coming from the vehicle, with the service brake assist message displayed. The brake pedal became firm, and the contact used excessive force to stop the vehicle. The contact pulled into a gas station and restarted the vehicle while the check engine light was illuminated. Despite the failure, the contact was able to drive the vehicle to the residence. The contact inspected underneath the hood and discovered an oil leak as well as black soot that had covered the entire engine. The dealer was notified of the failure and provided the contact with a diagnostic fee for an inspection. Upon investigation, the contact discovered NHTSA Campaign Number: 20V668000 (Power Train) which was linked to the failure. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 57,000.

My backup camera in my 2020 vehicle has failed twice. Once was covered under manufacturer's warranty, and it then failed again 14 months later, which is not covered under warranty. As explained by the dealer, a parts warranty is 12 months if covered under manufacturer warranty and 24 months if paid for by the owner. Different warranties for the same part? Additionally, there is a service bulletin out about this issue as MANY other owners are reporting the same issue. The camera parts are being damaged by "water intrusion". There is NO rust or damage that would be contributing to this, thus it appears to be a manufacturing defect. There is no way I should have had to replace this part twice with only 40,000 miles on the vehicle. (first time at 24,000 miles, second time at 38,500 miles). I feel that the manufacturer should be fixing these as they know it is a widespread problem.

The contact owns a 2020 GMC Terrain. The contact stated that rain water had leaked from the sunroof drainage into the vehicle causing the floor carpets to become saturated with water and mold had developed inside the vehicle. The contact also discovered a pool of water inside the spare tire well. The vehicle was taken to the local dealer who replaced the sunroof motor and sunroof liner, unclogged the sunroof drainage assembly and replaced the carpets. The contact indicated that later the failure had reoccurred although the sunroof drainage assembly was consistently unclogged each time the vehicle was in for service. The contact had also experienced respiratory illness due to the mold present inside the vehicle. The manufacturer was notified of the failure but no assistance was offered. The failure mileage was 12,300.

Driving down the road at 40mph when the car shifts to park, the brake and steering wheel lock up and the car won’t accelerate. I had to pull over because I almost crashed due to the abrupt shift. Once pulled over I tried to restart the car but once off and back on it wouldn’t allow me to shift or drive it. The steering wheel and brake remained locked. It has happened several times over the past week.