2018 GMC Terrain Powertrain & Transmission Problems

The contact owns a 2018 GMC Terrain. While attempting to shift to reverse(R) out of a parking spot, the message “Transmission Unable to Shift” was displayed on the instrument panel, and the transmission was unable to shift into reverse(R). The contact called for tow truck assistance. The vehicle was unable to shift into neutral (N). The contact stated that prior to the transmission failure, the “Service Transmission Soon” message was displayed. The vehicle was towed to a local dealer to be diagnosed, and it was determined that the transmission had failed and needed to be replaced. The vehicle was not repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 245,000.

April 2025, Vacuum Pump went out meaning lost breaks going 60 miles per hour down the road after engine light came on. Left me and two children stranded 2 hours from home with no way to get back except a tow. Now September 2025 Cam Shafts are out as well as Vacuum Pump. Stranded boyfriend and I two hours away again. Now metal in oil and warranty is not willing to cover it due to the vacuum pump going out. Made a post on Facebook and got lots of feedback on how their newer terrains have done the same things. Work in insurance and have people car pertaining to their terrains wondering if we cover engine replacements. There is major issues with these vehicle. Mine only has 107,000 miles on it and I have 12,000 left to pay. The motor is shot and dealership wants to “flush” the metal out of the engine. Very frustrated, I put 12,000 out of my college fund to have a reliable vehicle for my two kids and now this is all I have. A car that doesn’t run. I called warranty and the man I talked to even said that they get a lot of calls for these cars needing to be fixed. I am at a loss on what to do now. The below information about the incident is for the most recent one happening in September. I know that this sounds like a warranty and dealership issue but I guaranty if you send something out to terrain owners they will report major issues that they have had. Leaving them stuck in loans and no where to go.

The contact owns a 2018 GMC Terrain. The contact stated that while driving at an undisclosed speed, the unintendedly decelerated and failed to properly accelerate. The vehicle was taken to the local dealer, who diagnosed the vehicle with transmission failure. The contact was informed that the transmission needed to be replaced. The transmission was replaced with a used transmission, but the failure reoccurred. The vehicle was taken back to the local dealer who diagnosed and determined that the replacement transmission had failed and needed to be replaced. The vehicle was not yet repaired. The manufacturer was not notified of the failure. The failure mileage was 53,000. The VIN was not available.

The contact owns a 2018 GMC Terrain. The contact stated that while driving at various speeds, there was an abnormal grinding sound coming from the vehicle while transitioning to 4WD. The contact continued driving and the driving sound became more frequent while shifting into 4WD. Upon inspecting the vehicle, the contact discovered that the driveshaft had detached and was hanging down from the suspension. An independent mechanic was contacted, and the contact was informed about NHTSA Campaign Number: 17V516000 (Power Train); which the mechanic associated to the failure. The contact called two local dealers and was informed that the VIN was not included in the recall. The manufacturer was notified of the failure, and the contact was referred to the NHTSA Hotline to report the failure. The vehicle was not repaired. The failure mileage was approximately 160,000.

I bought this car used and had only had it about a month when I was driving to work and was in slow traffic on the freeway when my car slowed to a stop despite the fact that I had my foot on the gas pedal. It turns out it was a transmission failure. My safety and the safety of the drivers around me were put at risk because I was unable to move my car over to the shoulder and out of the lane of traffic. Traffic was slow but was still moving. My vehicle is available for inspection but I’ve already had it repaired so I no longer have the faulty transmission. The problem was confirmed by an independent service center where I had it repaired. The vehicle was inspected by the dealer and the independent service center. The dealer had it for 12 days but was unable to diagnose it so I took it to an independent service center. It was also briefly looked at and listened to by the highway patrol officer who assisted me and he also thought that the transmission had failed. The check engine light was on when this incident occurred but I was having an issue with one of the glow plugs and I thought that that was the reason. The check engine light came on the night before the transmission failed.

Timing chain. It had no warning and failed due to poor design and gm in Europe fixed/addressed the issue by installing a plate behind the tensioner a part that isn’t available in the us.

The contact owns a 2018 GMC Terrain. The contact stated that the transmission was shifting gear erratically. The contact stated that the doors were locking and unlocking independently, and the instrument cluster was blank. There was an abnormal beeping sound coming from the vehicle. Additionally, the contact stated that while at a traffic light, the Auto START/STOP feature delayed to respond. OnStar was alerted, but the contact declined to perform the service. The contact was in contact with the independent mechanic who sold the vehicle, but no assistance was provided. The local dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 130,000. The VIN was not available.

Hello. As I come to a complete stop the car will go into auto-stop. After releasing the brake pedal the car will jerk forward . As I press the gas pedal the car Jerks and shakes . The rpm jumps way up and the mph say low.. there's been times I try to accelerate and the car with jerk and put itself into park.. in the middle of traffic.. heart pounding to say the lease. I also notice theres alot of black liquid dripping for the front right side under the front bumper. There were no problems with the car or lamp indicating there were before this. I went to where I brought the car and they told me my warranty expired and that I will need to pay $265 just to diagnose the issue. I didnt have that money. I do have a car code reader and I did my best to find a solution. Codes P0700, P171D, And P187D all appear on my device. I then looked up recalls and my VIN wasn't confirmed.. but I am certain it is the same issue . You do have a open recall for this very particular issue for my particular model . I love my car and GMC. Please remedy this situation and have me driving safely and free minded again and soon ! Please reach back with any feedback as soon as possible. Thanks !

My check engine light comes on intermittently, since March 2024, after having Cabin & Engine air filters replaced. Each time, I’m told it is code P0171. This has happened too many times for my comfort. Usually, it happens around the time my gas gets below 1/2 tank or after I fill up my gas tank. Originally, I was told by the mechanic that it could be one of four things, of which I’ve now had some of things done. InIn Aug. 2024, the check engine light came in. Code was P0171. Mechanic replaced the Brake vacuum pump. Once incident, almost a month later, on 9/24/24, was very scary. While driving on the interstate, I got ready to increase my speed, but heard a pop sound and noticed the speed wouldn’t accelerate. Next, the check engine light came on and the message in the dash popped up saying “engine power reduced” or something similar. I was able to coast from the fast lane over to the slower lane and off the highway into a parking lot. I turned the truck off. When I crunk it back up an hour later, it was shaking and jerking. While slowly driving, on the way to the mechanic shop, it jerked and shook each time I tried to accelerate after stopping at a light or slowing down with traffic. The code again was P0171. According to the mechanic, the intake hose had popped off. On 11/13/24, the check engine light came on. I again took it to have the code scanned and truck looked at. Test results again showed P0171. This time the Mass Air Flow Sensor was suggested. In a year I’ve had the fuel system cleaned twice, brake system flushed, & other routine maintenance such as oil change & brakes. Yet, my check engine light seems to still come on intermittently atleast once monthly. It came on two days ago, 2/18/25, when my gas was around 1/4 tank full. I added a fuel system injector, per mechanic suggestion, and filled my tank up with gas on today, 2/20/25. The check engine light had gone off within about 15 mins of me driving. I’m certain it will be back on soon with the same code.

While driving the vehicle which only has 68,000 miles the reduced engine power warning light appeared. As quickly as was safe the car was pulled to the shoulder. It was towed to the dealer who states the Vacuum pump seized causing the camshaft phase actuator locating pin to spin. Originally they stated a new camshaft and vacuum pump were needed at $3,500, but now state the entire engine is damaged and must be replaced at cost of $12,000. The vehicle was well serviced and this manufacturing flaw lead to the vehicle be stopped on the road putting both the occupants and others around at risk.

Car is losing go power when accelerating on to interstate. It’s like the transmission loses power, the d illuminates, and then it kicks in to drive. It puts us at risk for an accident and I had a semi almost hit me because of this. This has been reproduced at the mechanic shop as well. No warnings before this happens

My vehicle put itself in park in the middle of an intersection while waiting to make a left turn in the middle of rush hour traffic. The car could not even be placed in neutral to be pushed out of the way of oncoming traffic. Narrowly avoided a collision.

The vacuum pump started leaking and the car was parked immediately. When The pump was pulled out to be replaced, the reason for the leak was identified. The vacuum pump had busted into small pieces which are now in the engine.

Transmission failed. Unable to purchase a replacement as there are no available transmissions for this year terrian.

While driving in the rain at about 25-30 mph I noticed a loss of propulsion and before I could turn off the main road the vehicle came to a rolling stop and would not recognize any gears. causing us to block the roadway and had to have it towed home. Took to local car dealer they said it RDCCM abnormal errors like u0422-00 and brake control module errors. Further diagnostics were need to figure out the cause and it possible that the Transmision is having problems now! This should be recalled.

There is an has been an issue with my electrical system says I purchased this car in 2017. Myself believe that the issues have not been documented until 2020. When my racy begins to run out, my engine light has been coming on and I’ve been getting the same code P1101 I took my vehicle to GMC and they told me that the engine light came on because the tape came loose. I brought this vehicle and there’s no way there should be no tape on it. The service tech also told me that if the problem continue to bring it back and I will have to pay $120 or whatever the label rate was for them to research I contacted GMC to file a complaint and I received the whole bunch of calls from a guy named Kevin. I believe he told me that he had been contacting [XXX] and no one returned his call and that he was sorry he couldn’t help me. This is my report number one of them from GMC. [XXX]. Everywhere I take my car they tell me that they have a lot of customers with the same issue and they tried to replace what the code is matching which is the mass airflow sensor but that does not help there is some type of problem with the engine or the electrical system with this vehicle. I am not the only consumer that has had this problem. I don’t know what to do. I have two kids I cannot afford to keep pay and label rate for them not to find the problem. I am also attaching the typical email that GMC sent out when they are working with the dealerships because I have been in contact with them and the person that was calling and then they sent me this email. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I have a 2018 GMC TERRAIN which I bought brand new from General Motors. In May 2022, the vehicle started jerking/hoping and trying to stall when the speed gets to 55 miles per hour or higher. I have taken it to the dealership on three different occasions for repair and I still have this issue. General Motors engineers were involved in every step of the repairs. They just do not know what is going on with the car or fix it and they are too stubborn. The dealership told me today that they cannot do anything else to the car. They also said they had a code from the engine last week and General Motors said they do not know what that code means. They are forcing me to accept/drive the car in this unsafe condition. I have contacted them multiple times and they do not care.

When you're sitting at idle in gear and go to accelerate the transmission will slip out of gear into neutral then into gear after the rpms climb. This happens alot. According to the dealership this is normal based on information from a bulletin from GMC.

11/24/2021 buy 2018 GMC Terrain, before leaving the dealership I told the seller that the engine light was on he said it was because they removed the alarm which I didn’t want to buy and the light was going to be off later and told me to take the car to service on Monday 11/29 so my husband took the car they repair a detail on the handle door and he said the engine light it’s off so we tough what he said about the alarma, we trust the seller but on 12/26/2021 I left California to Texas, I was about 4 and a half hours away the car began to lose speed and a very strange noise was heard, I stepped on the accelerator and did not raise speed, I had to step aside the freeway and the car turn on but It did not go forward or backward and NO warning light was on dashboard, nothin ! The car broke down in Arizona in the middle of nowhere, it’s was freezing and almost got hit by a semi truck, it was a very frustrated experience.

The turbine shaft in the transmission broke without warning. The part could have failed in an intersection leaving the vehicle in the middle of the road and potentially causing an accident as the vehicle was unable to move under its own power. Luckily it failed going down the interstate and my wife was able to safely coast to the shoulder. Yes, the vehicle was disassembled by the dealer and the broken part discovered. There was no warning that this would happen. The ironic part was that the vehicle was in to the dealer the day before for a emissions recall, a check engine light (emissions related) and a routine maintenance front end alignment and left my wife stranded the next day.