2020 GMC Terrain Problems and Top Complaints – Is Your Car A Lemon?

Vehicle speed control, electrical system and powertrain issues among the top complaints received by the NHTSA from vehicle owners

Updated on Author: Brian Jones

The 2020 GMC Terrain is a luxury-minded SUV that is designed to elevate the experience for customers. In fact, the GMC motto is “Like a pro,” but in this case, owners feel that the automaker missed the mark. For the time being, the Terrain seems to have a malfunctioning powertrain, vehicle speed control and electrical system.

Click on other model year to view more problems: 2019    2021    2022

Problems with the Transmission

The powertrain is supposed to be designed with a robust transmission that supplies energy to the wheels. However, this Terrain SUV is struggling to perform.

One Edmunds user puts it simply by saying, “Trans whines between 20-28 MPH.”

But, the issues go deeper than just the transmission making noises. Service Bulletin #PIP5720A also talks about one of the many major issues with the powertrain. It states that there could be a transmission fluid leak noticed, which looks like residual fluid from assembly. To determine if it is still leaking, a complete cleaning is required. New vehicles should not have any type of transmission fluid, whether it is currently leaking or was previously an issue. This doesn’t convince anyone that GMC knows how to do things “like a pro.”

2020 GMC Terrain Complaint Summary

Complaint CategoryNumber of Complaints
Service Brakes
Unknown Or Other
Power Train
Electrical System
Fuel/propulsion System
Vehicle Speed Control
Forward Collision Avoidance: Automatic Emergency Braking
Air Bags
Forward Collision Avoidance: Adaptive Cruise Control

Electrical System Problems

A vehicle’s electrical system has a big job. It must start the engine, run all of the accessories and supply up-to-date technology to picky users. When this system begins to fail, no one is happy.

Here is a complaint worth reading, left on the NHTSA website. “Every week it’s something different. In motion…no cruise control. No audio. Don’t drive over 50 mph brake problem. Parking brake engages randomly and without user engagement. No AWD. No Stability Traction. This happens so frequently the dash indicators have been reduced to Idiot Lights. At what point do I become concerned? Things appear to resolve when the engine is turned off and back on, sometimes…I compare it to other glitchy technology. However, I potentially could be at an 80 mph cruising speed when I decide to ignore the idiot lights…what happens when a real problem presents and I ignore the dash indicators due to frequent glitches? I’m so disappointed. My 2 previous Terrains were 10 times the vehicle the 2020 model year.”

It turns out that there are so many electrical system problems that GMC can’t keep up. One of the communications, Service Bulletin #PIT5745, talks about how the memory seat module can wake up the Lan BUS, leading to a parasitic battery draw. There’s nothing worse than running out to the SUV in the morning only to find out that the battery is dead and getting to work on time becomes impossible. This is a real problem, especially if the owner wants to make the money to pay the higher Terrain payments.

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Problems with the Vehicle Speed Control

The vehicle speed control is designed to help cars move at a specified rate, without much operator input. When this system fails, a lot of people are put at risk, as is seen with the Terrain.

Another NHTSA complaint states, “When cruise control is engaged at 71 mph, holding +Res Button to increase speed and releasing it at 77 mph sets cruise speed too high. Car continues to accelerate. Cruise gets set at 100 mph and accelerates more than desired.”

When it comes to this defect, GMC doesn’t want to talk about any problems. Instead, the automaker has allowed customers to drive blindly down the road, not knowing that it could accelerate on its own. Apparently, the Terrain is so focused on being a “Pro” that it also wants to move every other vehicle out of its way on the road.

Your Lemon Law Legal Rights

Think you have a lemon? Sit back and let the experts work out your lemon case at no cost to you. The law makes GMC pay legal fees. You may be able to get your lemon out of your life. Every year, auto manufacturers buy back, replace or pay cash settlements to thousands of ‘lemon’ owners like you.

Brian Jones

About the Author:

Brian Jones spent more than 30 years working as an ASE Certified Master Tech and Parts Specialist at multiple dealerships. Brian has become an authority in the industry, traveling across the country to consult for car dealerships and contributing his expertise as a writer for several major automotive publications. In his spare time, Brian enjoys working on pickup trucks, muscle cars, Jeeps and anything related to motorsports.

See more posts from Brian Jones
  • April

    I purchased a 2020 GMC Terrain SLT with 65000 ish miles on it. After driving the vehicle through fog and cold weather my check engine light came on saying that my engine power was reduced. Pulled code PO299, stating that my vehicle was under boosted. Brought it to where I got it from and they took it to their mechanic and they supposedly “updated” something to do with this issue.

  • Wilson19

    I have a 2020 terrain it’s rebuilt title with 3000 miles almost brand new a week later engine make a noise I took to the dealer it was a bad news the The crankshaft bearing it going bay it’s horrible

  • Ron

    After purchasing my 2020 Terrain in November 2019 everything was fine until I noticed grooves in the left front brake rotor at about 4500 miles. I usually change my oil at 5000 miles even though the manual states 7000 so I mentioned the grooves when I had the Oil& filter changed. The answer I got was that it must’ve been a pebble lodged between the rotor and brake pad. I let it go not believing that was the problem. After a couple weeks the grooves got deeper and I returned to the dealership and the car was given to another tech who discovered that the piston within the caliper had broken and part of it grooved the rotor. I had to leave the car for a couple days because they had to order a new caliper and rotor. Everything was fine until I noticed the grooves reappearing again in the new rotor. I once again returned to the dealership and was told it was normal wear. Right!!! Why were the other three rotors groove free. I waited a while and returned to the dealer and seen the service manager and told him all about this problem and said you guys replaced everything but the brake pads on the last repair. Sure enough the pads had something embedded in them so now I had to leave the car again so they could turn the rotor and replace the pads on both front wheels.

  • sadique J

    Worst and worsen car ever made in the world. car blast on the way and caught fire.

  • Gloria

    I have 2020 Terrain bought brand new other then some rattling underneath and other noises outside & inside I’ve had no real problems. Today I was going up a small hill and when I pushed the gas to go it made a clicking noise underneath and engine light flashing, Service esc, all wheel drive off flashed, wouldn’t go any faster. So upset I am now at GMC in York ruined my day! I hope they find a loaner if they need to keep 😭

  • Steve B

    We purchased a 2020 GMC Terrain in October of 2020 brand new. At around 15,000 miles my wife started noticing kind of a popping sound under the right side of the car. At about 23,000 miles I was driving the car and there was a loud bang from that side and the car shot me left across 2 lanes of traffic where i hit the curb before getting it stopped just missing cars at a used car dealership. When it hit the curb it rolled the right front tire into the fender by the door and broke the wheel. The car has been sitting at the GMC dealership for over 2 months and we have been fighting them about it being a defect. they are trying to say it was a collision but the only damage to the car is where the wheel rolled into the fender. there are no pot holes in the road and I do not have a clue what caused the bang.

  • LaShawn B

    I have a 2020 GMC Terrain purchased in Feb 2021. There is a transmission issue upon the first drive or so after the car has been sitting still. First in the morning or First in the evening after work it stalls. I have to take my foot off the gas and let it catch up. This is very disappointing as this is not the first purchase from the Chevy/GMC dealership that has had issues (both cars have).

  • Katherine D

    We bought our 2020 GMC Terrain certified used in may of 2020, the vehicle looks sleek and beautiful, the interior is nice, beautiful leather seats, however weeks after purchase we noticed the transmission seems to be slipping or not engaging at very very erratic strange times! Often is putting it in drive after reversing the vehicle won’t go and then we it does it shoots forward. I’ve nearly been in a handful of wrecks as well as my husband. I have taken it in to Chevy where we purchased 3x now and left it with them and the “can not replicate the issue” I said if you google search my vehicle it’s the first issue that’s reported across the board, it is always been reported in their bigger SUVs and trucks, there have even been recalls and class action lawsuits. We got this SUV to have for the next 5 years and it’s simply unsafe to keep. I even contacts GMC directly and they are no help.

  • Tom H

    I have a 2020 Terrain 2.0 Elevation Edition. I have 0 issues except an annoying rattle on the passenger side A-pillar area. I just hit 17,448 miles and bought it new. Love the car otherwise.

  • George E

    I own a 2020 GMC Terrain, and occasionally the cruise will turn off by itself, and won’t come back until I turn the car off and leave it for 10-15 minutes. The radio sometimes will not let me change the channel and the traction control light comes on by itself. Again, it will all reset after I turn the car off and walk away for a few minutes.

  • Pam D

    I own a 2020 Terrain and love it. 5,800 miles so far and it’s only been taken back to dealer for scheduled maintenance. I sure hope it stays this way. I am always concerned about the engine constantly cutting off and on again. Now I don’t even notice it. There are lemons, I know, years ago I bought a new Jeep Grand Cherokee and had to return under the Texas Lemon Law. I sure hope the best for the GMC Terrains and their owners.

  • Dennis A

    Lights and turn signals fail regularly, Repeated trips to dealer for repairs, problems are intermittent and they day bring it in while is happening. Of course, when the car is switched off and bac on there appears to be no problem. Power train is sometimes jerkey at 55 to 60 mph. It usualy, takes me some time to hate a car,but not this thing,3 weeks in I hated it.

  • Michon H

    We purchased our 2020 denali Terain a year ago and have had it into the dealership 4 times now due to check engine light coming on. The first time they said it was a sensor, but of course it went off the day we took it into the dealership and told that if it comes on again bring it back in. The second time the check engine light came on I took it and they “supposedly” replaced it. Then it came on a 3rd time, this time I was told that the “motherboard was bad” supposedly they replaced the entire system. Just last week the check engine light came on again. Just took it into the dealership again to find out what it is this time.

  • Reem I

    My problem in terrain 2020 is that car’s smoke enter my car cabinet when ac/heater is turned on even during internal circulation mode.
    I bought it brand new from gmc agent in jordan and they told me that problem can not be solve

  • Casey H

    I purchased a new 2020 Terrain with 32 miles from a local GMC dealer. At 350 miles the power steering failed, nearly causing me to crash. The entire steering column was replaced by GM at mile 1,140. Now at mile 3,900 there was a loud pop under the hood, while driving with the cruise control set at 60mph, and the vehicle is in limp mode with the check engine light on. The engine stalls at low rpms and it looks like I’ll miss work to take it back to the dealer tomorrow. I’m ready to be rid of this thing!

  • Dave M

    Every manufacturer and vehicle model has lemons no doubt. Your comments here make it sound as though all GMC Terrains have terrible problems. Being in IT, I know you can look on forums for software/hardware problems and you will find them to the point you will wonder how the product even works! I own a 2020 GMC Terrain Denali for over a year now and have experienced none of these issues — I hope I don’t — and expect the vast majority of owners will not.

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