2020 GMC TERRAIN Engine Problems

I noticed a sticker in driver door stating recall however no evidence. The vehicle will not pull hills, back up on a hill and will not accelerate over 25 miles per minute. Dangerous to drive on roads. Took vehicle to a GMC dealer for diagnostic test, received the report for what the report found. Took the report to auto shop to get repaired however the vehicle still continues with same issue. Took the vehicle to another auto shop. I was informed of some differences added issues. I had those issues fixed. The vehicle still running the exact way after all of the repairs. The top hood on the vehicle paint starts peeling after a year of owning it. I purchased the vehicle at Kia of Gardendale 2020. No one had any answer regarding the situation. Very disappointed with a GMC vehicle. I just want to know the mystery.

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...

The intercooler has been a document problem on GMC Terrains for awhile now. I had my intercooler replaced and now less than 10 months it is having the same problem. The vehicle will go into reduced power mode which would be a safety hazard because it will also stall sometimes when it is having performance issues. That could lead to someone colliding into me if it suddenly stops when someone is behind me. I believe this part should be recalled and fixed for free.

My a/c went out within 2 years of having the car in 22’. In 2025 i have had nothing but problems, the radio will go out when im driving for about 2 hours and it resets, the screen goes black, music stops, navigation stops and then it turns on like nothing happened. It happens everytime I drive 2+ hours. Back in September of 2025, I was on my way to work when I was stopped at a red light, it turned green and then my brakes locked up and I couldn’t drive my car had shut off, and wouldn’t come back on. I was stuck in the middle of the road not knowing what happened as the car had driven fine up until i stopped at the red light. Then tonight November 21,2025 around 0315 I was leaving work, I started my car, my car threw up a message that...

From a complete stop my car refused to accelerate no matter how much I pushed the gas pedal. I was pulling into traffic and was on a hill so my car rolled forward naturally into the road but would not respond to the gas pedal. The RPMs didn't move, the car had power, I tried putting it in reverse and then back into drive. Nothing worked for a solid 2 minutes at least. Then all of a sudden it registered and worked. I was almost t-boned from a car coming through the curve but luckily, they were able to go around me in time. This put me and my small daughter at risk of being severely injured from a malfunction that I can't recreate to show the technicians. Since this incident, it has happened several times randomly. Sometimes I'm at a red light, or backing out of a parking spot,...

First problem was when the ac went out which affected the starter 2 weeks after that while I was driving something popped underneath the vehicle the vehicle completely stopped working when I checked underneath the vehicle there was leak ish a broken crankshaft car would not turn back on….

Driving down the road and an engine power reduced light came on and then the driver was not able to apply the breaks to stop the car. Almost ran into a car at a 4 way stop before getting the car to stop.

Driving down busy highway and suddenly had no brakes!!! No lights came on dashboard as a warning. Found out it was a braking pump that broke and shot metal pieces into the engine. Now im facing a new engine for a 2020 terrain!!

I have been having intermittent problems for well over 1 year with my vehicle not accelerating. I try to accelerate from a stop, the vehicle does not respond. I have the accelerator pedal pressed to the floor nothing happens for 10-15 seconds, then vehicle will lurch forward and start responding. This has happened several times as I am pulling into traffic. Major safety concern that could cause severe injury or fatality. I also have other issues with vehicle not shifting gears, engine feels as though it is skipping while driving. I have taken this to the dealership and was told that they could not recreate the issue. No engine code or service lights have ever displayed. Dealership told me is can't be anything major since there are no codes or service lights. Currently have 72,000 miles, did purchase an extended warranty. I have seen many complaints of this same problem...

As I was driving down the Ohio Turnpike on my way to work on Tuesday, August 5, 2025, my check engine light came on. Almost immediately I got a notification that the car was operating at reduced power. I had no previous issues with the vehicle. As I got off the turnpike my braking system failed. I was able to come to a stop partially in the grass before entering into oncoming traffic. The entire car shut down. I was unable to restart the car. We were also unable to put the car into neutral to push it off of the road the remainder of the way because the wheels were completely locked up at this point. The parking brake was engaged on its own. We also could not get the car into neutral. I had the car towed to a local repair shop, not knowing at all what the...

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.

The contact owns a 2020 GMC Terrain. The contact stated while driving at an undisclosed speed, the vehicle lost motive power with the check engine warning light illuminated. The vehicle was towed to an independent mechanic, where it was diagnosed that the fuel pump control module had failed and needed to be replaced. The vehicle was not repaired. The dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure and referred the contact to the NHTSA Hotline for assistance. The approximate failure mileage was 88,000. The VIN was not available.

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.

On 6/22/2025, brakes stopped working while trying to make a turn. Next multiple engines light came and car went into reduced speed mode. As I tried to find a safe place to stop, the vehicle went into limp mode and shut down in the middle of the road. The dealership said the issue was the vacuum pump which caused the timing chains to break. There have multiple recalls for this exact issue but my car is not on the list. My manufacture warranty ended on 5/21/2025. When I spoke to a GM representative I was told there was nothing they can do because there is not a recall for my vehicle. They explained even though I had the same problem the recall is for other vehicles. GM also issued a warranty extention on the vacuum pump to 10 years 150,000 miles. However my vehicle is not on the list for...

While my wife was driving on [XXX] speed (60 –70 mph), the engine suddenly seized without warning. This created a dangerous situation, especially at that speed. Upon inspection, it was confirmed that a camshaft end cap detached, causing catastrophic internal engine damage. I believe this may be due to a manufacturing defect or insufficient part durability, and poses a serious safety risk to myself and other drivers. Please investigate this issue for broader safety concerns and potential recalls, especially if other owners report similar failures. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

[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...

5.25.2025 - Car shut down while at a busy intersection. Called Amherst Police due to location and how dangerous the intersection was. Family member needed to jump start the vehicle. Vehicle started before police arrived. Drove home. Called police to let them know we were no longer at the busy intersection. 5.26.2025 Took out battery to check charge at Auto store - tested Good - 82%. Re-installed battery went to get gas thinking that may be the issue, low on gas, not the case the car wouldn't start at the gas station. Family member needed to jump start the vehicle again. Drove home, called dealer, taking to dealer next week 6.4.2025 due to availability of service. There were no warning lights prior to stalling out both times. This is very dangerous. We are afraid to drive this GMC 2020 Terrain.

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.

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.

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...

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.

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.

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.

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.

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.

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...

On 4/10/2023, I took my vehicle to a local GMC dealership because it was stalling and didn't have any power. Upon accelerating the vehicle it would stall and take off at a high speed. The dealership has had my vehicle periodically from April 2023 and it presently sets at the dealership because they ain't getting a code, But after the dealership drove the truck for over 200 miles, they were finally able to duplicate the stalling yet are not able to diagnose the problem!! This vehicle is very dangerous to be on the road and I have almost gotten hit twice and I'm not driving the vehicle anymore at this time. I have previously reached out to you all and I would be most thankful if you could get in touch with me. Thank you

GMC 2029 Terrain Our car broke down three times after a new engine was put in. After one week it had to be towed again to put in a third new engine. It has been fixed since Aug. 1st but GMC has yet to reunite us with the car 2000 miles away. We’ve made car and insurance payments for almost three months with no vehicle in our possession. It was under warranty. No loaner or rental car has been issued to us. Nobody calls us back. Terrible customer service by GMC.

2020 GMC Terrain Engine stopped working. Put in new engine. After one week new engine blown. We were 2000 miles away on vacation. I need a free rental I was with no car for a month and after only one week again for 3 weeks. Compensation request: Lost wages Hospital visit Extra hotel nights Gas Food car and insurance payment

While on highway service brake system warning light came on,brake became hard to apply almost causing an accident. Vehicle had to be towed to a repair shop(dealer).after paying over $1600 the problem was not resolved and found there are numerous complaints about issues with the terrain and no recall issued.are they waiting til someone dies before a recall?

My vehicle begin stalling when accelerating (mostly after stopping) June 2023. My vehicle has almost cause me to have two accidents because it intermittently stalls when I try to cross an intersection. This is my fourth time taking my vehicle to the GMC dealership, and they tell me they can't find anything wrong if there is not a code. I have reached out to Corp, and I'm waiting to see if they can help get to the bottom of my problem. My car has been sitting at the dealership since June 30th 2023....I call the dealership periodically, and they never reach out to let me know what's going on. I am afraid to drive my vehicle at this time because next time another car may not be able stop and give me time to get across the road. I'm filing this complaint because I seriously think someone is gonna get...

2020 GMC Terrain SLE Elevation Package 83,000 miles and needs complete engine rebuild @ cost of $10,700 per Dealership Service. Was told “I drove the vehicle with low oil” which Inturn is the cause of needing engine rebuilt. I have had this vehicle serviced, oil changed regularly etc NOT ONE TIME has the oil pressure/low engine oil nor anything related to oil illuminated on my dash. CEL yes after it apparently was too late and damage was done which showed code P06DD And P0324 through OnStar Diagnostics. There are also other complaints with same issue, and no notification of oil /oil pressure issues with relatively low mileage that have led to engine rebuild. I still owe on this vehicle through GM Financial, and a $10,200 engine rebuild on top of that… Not what I would expect out of GMC~

My 2020 terrain is now at 33k+ miles, I have had repeated instances with my car not accelerating properly. I would be at a full stop try to start to accelerate and not move push down a little further on accelerator and start crawling forward. I would move approximately quarter mile before the vehicle would jerk and accelerate very quickly to a speed well over where it should go to. I.e. I know because I’m starting in traffic I’m not trying to take off at thirty but when the jerk happens I can be jolted to 40-45 mph. The other issue is people behind you don’t realize what’s going on and I have been hit almost twice thankfully they were able to avoid me by going around. No warning lights have come on. This last insistence not only could I not accelerate, but cruise did not want to turn on,...

This GMC I just purchased in October 22 2022 and have been complaining since December 9,2022 the vehicle emergency braking will activate when I'm driving down the interstate or local roads I could be doing 70 and brakes will just lock up throwing me and my son forward , this has happened 4x , Gas Pedal when taking off at red light or pulling out the vehicle is hesitant and will not go this has happened on 3 different occasions. I called roadside on star they said there is a problem with the on star saftey feature will not work properly this was towed 2x to different shops, Also while driving this vehicle it will just ingage itself in park while driving called on star they did diagnostic there was all kinds of Coded for Transmission and Engine as well as Emissions this vehicle is a safety hazard.. And I...

The engine cutoff while driving through a major intersection in 3/2022 with no warning lamps, messages or other symptoms of the problem prior to the failure. Dealership replaced the fuel pump module. Subsequently, the engine cutoff while driving in 5/2023. Dealership replaced the fuel pump module. Each of these occurrences placed my life, my passengers life and the lives of others on the road in danger as an accident could have resulted if I was not able to coast out of harms way. GMC has an existing recall on the fuel pump module for 2021 - 2022 Chevrolet Equinox and 2022 GMC Terrain vehicles. Why did this happen a second time after replacing the fuel pump module? Are they using a module included in the recall? I was charged $ 591 dollars for the repair in 3/2022 and no charge in 5/2023 as they stated it must have been a...

I was driving down The expressway. The traffic in front of me came to a stop. When I went to apply the brakes I had no breaks. The pedal was as hard as A rock So when I realized I couldn't stop I swerved over into the breakdown lane. And continue to pass cars at a high rate of speed until I got the car to stop. There were no check engine lights on Then I had the car towed to the Dealership Where they tell me is a break vacuum pump. That has damaged The Cam shaft. Pistons and rods in the engine. Totaling $7200. In damage. No one seems to care and I still owe 20000 on the car. Car has 71000 miles on it.

The contact's friend's son owns a 2020 GMC Terrain. The contact stated that while her friend was driving at an undisclosed speed, the brake pedal went to the floorboard while depressed. The brakes failed to immediately stop the vehicle. Additionally, the vehicle made grinding sounds while driving. The vehicle was taken to the dealer, where the vacuum pump, exhaust camshaft, and valve cover gasket were replaced; however, the vehicle lost motive power while driving. The vehicle was towed back to the dealer, where it was determined that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and informed the contact that there was no recall associated with the VIN. The failure mileage was approximately 48,552. The contact stated that additionally, the check engine light came on without cause. The contact is unsure why that is because a diagnostic test had...

I just purchased this vehicle about 2 weeks ago, and was driving through the fog/cold weather and my check engine light came on. Went to O'Reillys and had them check the code. Came up as P0299 (My car was telling me that the engine power was decreased) I had a loss of power I could feel while driving as well. The code said turbo under boost. After I got back into town and the weather was warmer and no fog was present, the turbo started working again. I brought my vehicle into the dealer where I bought it from and they took it to their mechanic and supposedly performed an "update". I will see if I continue to have the same issue in cold weather as I live in Idaho and go to the mountains often.

Turbo failed. Car ran fine with no warning lights. Stopped at red light entering interstate and then could not accelerate which left us stuck in traffic. When it did move it would not shift and took over a mile to get above 20mph in a 65mph zone.

The engine will never go into 9th gear! What's the point of GMC doing a 9 gear transmission to help with fuel, if it never actually goes into the 9th gear?

UNKNOWN...ACTS AS IF ITS A SMART CAR THAT'S NOT REALLY A SMART CAR

As I was driving on the highway in New York on Route 17 south near exit 111, I tried to accelerate but when I did the car went slower and the check engine light and traction control lights came on. I was right in front of a huge truck and thank God I was in the right lane that I was able to quickly get on the shoulder and turn the car off. I was able to make it to where I was going, but it was very nerve wracking. I took the car to the dealer service center and was told that it was probably a fuse issue. It turns out my entire engine has to be rebuilt. I have approximately 25,000 on my car, how could it require an entire engine rebuild? The dealer has gotten me two rentals cars that only last 5 days at a time...

This 2020 GMC Terrain has a "feature" called autostop. This is not a switch to turn this off. It would not be so bad if the engine would run for 5 minutes at a stoplight before stopping the engine but it immediately shuts down the engine after a stop. This is getting annoying and dangerous due to the delay in getting the car moving. I have only had the car for a month. I understand that later gmc cars have a disable switch. This car should be recalled and either disable the auto stop permanently or be able to disable the "feature" on demand. Problem: potential crash hazard due to car not starting and damage to battery and starter.

loss of oil due to engine defect and need new engine. engine and car at dealership. engine has not been torn apart to find cause. occupants could have died because of engine stoppage... GM wants owner to pay over 15,000 for new engine and instillation. car under new car warranty has 24211 miles. no early warning lights of low oil.... Owner took car in immediately when warning lights appeared 9-27-21 and GMC dealership improperly serviced . on 10-14-21 same warning lights reappeared and taken immediately to same close dealership. Now told new engine needed.

WE DROVE TO A FARM WITH A FAMILY OF 5M KIDS AND AN ELDERLY, AND PARKED MY CAR FOR 2-3 HOURS IN THE FARM'S OPEN AREA PARKING LOT. VEHICLE SHOWED NO WARNING LIGHTS, NO PROBLEMS, NO ISSUES DURING OUR DRIVE TO THE FARM AND PRIOR TO THIS TRIP. EVERYTHING WAS FINE WHEN WE GO THERE AND PARKED. WE WERE READY TO LEAVE THE FARM TO DRIVE BACK HOME, BUT THE CAR SIMPLY WOULDN'T START.THE NEUTRAL GEAR DIDN'T WORK, I ATTEMPTED MANY TIMES IN 30 MINUTES TO START THE CAR, BUT IT DIDN'T START, CONTINUED MAKING THE SOUND OF ENGINE ATTEMPTING TO START BUT NOT SUCEEDING. 30 MINUTES LATER, I DECIDED TO GIVE IT ANOTHER TRY, I WAS AFRAID TO BURN DOWN THE STARTER AFTER ATTEMPTING SO MANY TIMES. IT SOUNDED TERRIBLE, SCREECHING METAL SOUND. ALL OF A SUDDEN, THE CAR STARTED. I LET IT RUN, AFRAID TO TURN IT OFF...