Engine And Engine Cooling Problems of GMC Terrain - part 1

While driving my 2019 GMC Terrain on local roads, the vehicle suffered a sudden and complete failure of the braking system. The brake pedal became extremely hard to press, and the dashboard displayed a critical error message stating 'engine power is reduced. ' during this frightening safety incident I felt lucky to bring the car to a stop without an accident. The vehicle had to be flatbed towed to a repair facility. This sudden loss of power braking is a known, documented defect matching the engine-driven brake vacuum pump failures currently subject to federal class-action litigation (thieme v. General motors). I am requesting a formal safety investigation into why the GMC Terrain was excluded from previous gm vacuum pump recalls despite posing an identical, life-threatening risk to occupants. ".

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At 12,000 miles removed old air filter found grass under air filter.

While driving my 2018 GMC Terrain, the vehicle suddenly displayed an “engine power reduced” warning and the brakes became extremely hard to press. The vehicle experienced a sudden loss of normal power-brake assist while it was in motion, creating a serious safety risk because significantly greater pedal force was required to stop the vehicle. I was able to pull over safely. After stopping, the vehicle would crank but would not start. The vehicle was towed to a GMC dealership for inspection. The dealership documented that the vehicle had a suspected failed/broken vacuum pump, a damaged exhaust camshaft, and a damaged exhaust camshaft actuator. The dealership subsequently documented that the engine was severely sludged and stated that the sludge caused the vacuum pump to fail, which then caused the exhaust camshaft to twist and damage the exhaust camshaft actuator. The dealership’s written diagnosis recommends replacement of the exhaust camshaft, exhaust camshaft actuator, vacuum pump, and associated one-time-use parts. The dealership has also documented diagnostic trouble codes p0014 and p0017. The failed vacuum pump and related components should be available for inspection upon request. The vehicle has been inspected by a GMC dealership, which has documented the suspected vacuum pump failure and resulting engine damage. The sudden loss of power-brake assist occurred while the vehicle was being driven and created a potentially dangerous loss of braking capability. I am reporting this because I believe the failure of the vacuum pump and resulting loss of brake assist may represent a safety-related defect requiring investigation, particularly because the vehicle experienced a hard brake pedal without prior warning.

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The vehicle has had regular maintenance, oil change, and inspection including the brakes. My boyfriend is visiting me in [xxx] from the [xxx]. Onxxx while driving the vehicle the engine started. Making a ticking noise especially during idle and when accelerating in idle. About 15 minutes after the ticking stopped and all of a sudden there's a complete loss of breaks they locked up and the driver was unable to efficiently stop while going down a hill road. Driver had to use the emergency brake to make the other brakes release and then the brakes from there would not work even though you could stomp on them stand on top of them there was no breaking power anymore. Vehicle was brought into a GMC dealership on the following Monday where they confirmed the issue was a failed vacuum pump connected to the engine and camshaft which is a known safety issue to GMC as part of an ongoing open case they had specialty coverage and bulletins regarding the tahoe and sierra but neglected to include the Terrain on this issue. Cold the GMC manufacturer in both [xxx] and [xxx] to try and get cost assistance and specialty coverage as the vehicle as well under the mileage requirements but have been giving the push around and zero assistance. The risk to the drivers and passengers lives was significant as we were on the highway for1. 5 hrand thankfully the brake lost didn't happen in full during that time. The repairs were completed and paid for in full by the client which should have been covered by the dealership and we are looking for cost recuperation and are now being ignored. Receipts are here to substantiate the claim. The abs light is no longer on there was no warnings on the vehicle showing any issues or any codes as onstar was called and diagnostics were received and the diagnostics came back clear prior to this happening, and following the break failure. Lack of codes and warnings is life-threatening and serious. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Vacuum pump failure causing sudden and unexpected hard brake pedal and loss of braking coming off the highway. Ended up catastrophic engine failure. This is the second incident with this vehicle of the exact same problem. GMC refuses to address this issue and continues to risk the lives of their customers.

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Since purchase, this vehicle has consistently had an issue with the fuel system. When I call GMC they state only use no ethanol fuel. I wouldn’t have bought this car if that was the case. The dealership never said that when I was buying it. We replaced the entire engine for $11,000 because of a torn radiator hose, overheating and cracked a gasket. Now, the car is refusing to drive, giving engine power reduced.

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Accelerator lag from any speed or stop. The care will take several seconds to hunt for the correct gear before shifting to accelerate. Or it will delay acceleration for several seconds while your pressing the accelerator. No ses indicator active. Mechanics can’t find issues. Other owners on forum a report the same sluggish behavior. These 1. 5 turbo cars seem to need a software fix that they are not receiving. It’s like the drive by wire doesn’t register. Affects any gm vehicle with the 1. 5 turbo and 9 spd auto.

The contact owns a 2022 GMC Terrain. The contact stated that while his wife was driving 35 mph, the contact received an email and text from onstar with dtc: p129f, and the message to not drive the vehicle was displayed. The check engine warning light was illuminated. The vehicle was taken to the local dealer, where it was diagnosed and determined that the fuel pump power control module had failed. The vehicle was repaired, but the failure reoccurred. The contact stated that the failure was related to n252516900, a general motors (gm) emission recall related to the fuel pump power control module (fpcm and gm safety recall n222372310 – inadequate fuel pump flow. The local dealer was contacted, who stated that the fuel pump had failed to meet higher outputs. The manufacturer was contacted and confirmed that there was no coverage on the vehicle. The failure mileage was approximately 66,000.

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On June 7, 2026, I was driving my 2020 GMC Terrain. I was going at about 40mph along a very busy main road. While slowing for a red light the check engine light turned on and the car displayed a notice about reduced engine power. Seconds later, the brake pedal became stuck and would not press down all the way and I lost braking ability. The car rattled/shook violently, made a grinding noise, and then the engine shut off and the car stopped abruptly, narrowly avoiding hitting the car in front of us. I turned on the hazard lights. I was not able to get the car to start again, nor was I able to get the car to shift into any other gear including neutral. We were nearly hit by other vehicles multiple times while attempting to get the car to move again, and to get myself and my child safely out of the road. Myself and multiple bystanders attempted to engage the transmission interlock override multiple time. We were eventually able to engage it and push the car to the side of the road. This failure created an extremely unsafe situation for all involved as this road is very busy and there were numerous near-collisions both with my disabled vehicle, and with other drivers serving out of the way and into other lanes at the last second. As time went on and the battery drained, most of the car's exterior lights turned off and other drivers had a hard time seeing my car. I used a strobe flashlight to alert other drivers but this required that I had to stand in the road near the vehicle. Police were called immediately when I found that we could not move the car out of the road, but they did not arrive. Ultimately the vehicle was stuck and inoperable in a travel lane for over two hours. The car was then towed to a nearby repair shop. The mechanic evaluation stated that the brake vacuum pump had failed resulting in loss of braking ability and expensive damage to the engine and other components. The manufacturer is aware of this issue. See: thieme, et al. V. General motors llc.

During my daily commute to work on the interstate the service break assist message came on my dash and when attempting to break the pedal was very hard, to the point where I had to push extremely hard and quickly realized I had to brake much much soon than normal to prevent hitting other vehicles. Sudden loss of brakes put me and other drivers at risk due to my near inability to slow down or stop and the sudden and unexpected nature of the event.

I am a [xxx] resident. While commuting to work in [xxx], my GMC Terrain experienced a sudden, catastrophic failure of the brake vacuum pump while traveling at highway speeds. When I attempted to slow down for the exit, the brake pedal instantly became extremely stiff and nearly impossible to depress. I realized I had suffered an absolute loss of power braking assist. To avoid a high-speed collision with heavy highway traffic, I was forced to deliberately steer onto the roadside rumble strips, relying on tire friction to slow the vehicle down. This severe near-miss left me terrified and distraught. Because the shoulder was narrow, my disabled vehicle was left partially protruding into the active roadway. Passing cars sped by so close that my vehicle was violently rocking, creating an incredibly unsafe situation. I was forced to call the state police for emergency assistance. They dispatched a trooper and a tow truck to remove me and the vehicle safely from the highway. The vehicle was towed to a mechanic in massachusetts. The mechanic discovered that the vacuum pump had internally exploded. This explosion sent catastrophic metal shards and debris directly into the engines oil galleys and oiling system. While the vehicle has 121,776 miles, this is not a normal wear-and-tear component failure. The brake vacuum pump suffered a catastrophic internal mechanical explosion at highway speeds, completely eliminating my ability to stop the vehicle. A mechanical component failure should never cause an immediate, life-threatening loss of brake control, regardless of mileage. This is a known, systemic engineering defect that is currently the subject of active federal class-action litigation (xxx v. General motors llc). This defect did not just cause an immediate life-threatening braking failure, it completely contaminated the oiling system, destroyed the entire engine, and rendered the vehicle a total loss requiring a full engine replacement. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552.

The contact owns a 2023 GMC Terrain. The contact stated that while driving at various speeds, the vehicle unexpectedly decelerated and failed to properly accelerate. The service transmission and service fuel management system messages were displayed, and the check engine warning light was flashing with several other unknown warnings illuminated. The vehicle was taken to the local dealer and while test-driving the vehicle, the vehicle stalled. The vehicle was towed back to the dealer. The cause of the failure was not yet determined. The manufacturer was notified of the failure, and an engineer was sent to the dealer to inspect the vehicle. No further information was available. The contact stated that the transmission module was previously replaced, but the failure persisted. The failure mileage was 27,000.

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My car has started stalling and dying when I slow down, take off or when idling. No power when accelerated, and the smell of exhaust comes into my car. I was making a turn from a red light and my car spit, sputtered, and died right in the middle of the busy intersection. I was almost hit from the rear and another car had to go into on coming traffic to avoid t boning me. I took it to 2 different places to get a diagnosis reading and both places said it was a catalyst problem, and I was told that there was a recall about that because of engine oil clogging it up. My car has been using more oil than usual here lately and im guessing thats why. Now, im afraid to drive anywhere because I don't feel like it safe and the fact that my car doesn't run good enough to drive. I was told by more than 1 person that knows mechanics, that its a issue with the catalyst and that it had a recall on it but I never received one. This is a very concerning safety issue, and one that needs immediate attention before someone gets badly hurt (or worse) because of a bad car part . My car is literally just a lawn ornament now until I can get this issue resolved. I need my car to make a living and support my family. Please, get the recall letters out and get this fixed before someone loses a life.

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Transmission wouldnt shift. Sensor in car is causing issue, code is n 202321840.

I am submitting this complaint regarding a serious and dangerous brake failure involving my 2020 GMC Terrain slt with approximately 150,000 miles. While driving, the vehicle suddenly experienced a vacuum pump failure that caused a severe loss of braking ability with no warning beforehand. The brake pedal became extremely hard, and the vehicle would barely stop. This created a very dangerous situation and could have easily resulted in a serious accident. Thankfully, I was not driving at a high speed when the failure occurred, and there were no vehicles directly in front of me at the time. However, only minutes earlier I had been traveling approximately 65–70 mph on the highway. If this brake failure had occurred while driving at highway speeds or in heavy traffic, I truly believe it could have caused a major crash resulting in serious injury or death. What concerns me most is that there was no warning before the brakes failed. No warning lights and no issues with my brakes. The sudden loss of braking power was extremely frightening and created an immediate safety hazard. After researching this issue, I discovered that other GMC and gm vehicle owners have reported similar vacuum pump failures and brake assist problems. I believe this is a significant safety issue that should be investigated further. Drivers should not experience sudden brake failure without warning, especially on a vehicle that otherwise appeared to be operating normally beforehand. I am very thankful no one was injured in my situation, but I am concerned that another driver may not be as fortunate. My vehicle had to be towed to a nearby shop and they suspected it was the vacuum pump failure and the car started smoking badly. So I had it towed to the GMC dealership and they called me today to confirm that was the problem and it also caused damage to the camshaft. This is a known issue with the Terrain and there is currently a class action lawsuit.

I am submitting this complaint regarding the engine timing chain failure in my 2015 GMC Terrain because I believe it presents a serious safety hazard. Before the failure, the vehicle began experiencing intermittent symptoms, including engine jerking, shaking, rough operation, abnormal engine noises, and an intermittent check engine light. While driving on the highway, the engine timing chain failed, causing the vehicle to suddenly lose power. I was traveling at highway speed and had to safely maneuver the vehicle out of traffic. The unexpected loss of power placed me and other motorists at risk of a collision because I could no longer safely maintain the flow of traffic. The vehicle was towed to an independent repair facility, where the engine was diagnosed with a timing chain failure. I was informed that the engine had sustained significant damage and required replacement. After purchasing and installing a replacement engine, that engine also began exhibiting timing chain-related symptoms immediately after installation, including abnormal rattling noises and unstable engine operation, resulting in additional repairs and the vehicle remaining unsafe to drive. I am concerned that timing chain failures in this model can occur without sufficient warning and can cause a sudden loss of engine power while the vehicle is being driven. A sudden engine failure at highway speeds creates a significant risk of a crash, injury, or death. I am requesting that this issue be investigated to determine whether it represents a safety-related defect affecting other 2015 GMC Terrain vehicles.

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I have had 2 different instances where my vehicle stops in the middle of a busy intersection or traffic and have no warning what so ever. Vehicle just shuts off and I am not able to turn back on to move out of the way. First time I got it repaired it was related to the fuel pump and now I am waiting to hear back from my mechanic to see what the issue is but so far it is an indication of the fuel pump as well. Both times I required help from law enforcement because vehicle shut off in the middle of the road and safety to myself and other drivers was an issue until tow truck arrived to move my vehicle.

The contact owns a 2019 GMC Terrain. The contact stated that while stopped and attempting to turn to exit a highway ramp, he observed a loud banging noise emanating from the engine compartment. An "engine reduced power" message appeared. The vehicle then went into limp mode, and when the brake pedal was depressed, it was stiff as a rock. The vehicle coasted while he continued attempting to depress the brake pedal, and it eventually slowed down. The vehicle was steered to the side of the road and turned off. When the vehicle was turned back on and he attempted to depress the accelerator pedal, the vehicle did not accelerate. The vehicle was taken to his mother's residence approximately 100 miles away in limp mode and parked. The vehicle was not diagnosed or repaired. The contact stated that his brother, during an inspection of the vehicle, removed the vacuum pump and noticed that it was broken with numerous pieces that had gone into the engine. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 76,000.

My 2016 GMC Terrain 2. 4l ecotec first stalled while idling at a red light in raleigh, nc. I restarted it and it sounded different, so I drove it home. The next morning it would not start. The failure occurred at approximately 69,939 miles with no meaningful warning. The dealer’s diagnostic report states there were no current relevant codes and no relevant codes in history. The dealer documented major timing-system failure: timing chain tensioner failure, timing chain guide failure, a timing chain guide bolt pulled out of the cylinder head, aluminum contamination in the cylinder head/oiling system, and engine replacement recommended. The vehicle was found unsafe to operate. This vehicle regularly transported my family, including my children. If the stall/no-start failure had occurred at highway speed, while merging, or in heavier traffic, it could have created a serious crash risk. The oil was maintained outside the dealership network and had been serviced before failure. I also topped off the oil shortly before this occurred. The 2. 4l ecotec engine family is known for oil-consumption issues, yet this vehicle gave me no direct warning that oil consumption had reached a dangerous level. A reasonable owner would not know to check oil every day when there were no relevant stored warning codes. Other NHTSA complaints involving 2016 GMC Terrain vehicles describe similar patterns: oil consumption, no warning lights, sudden stalling or no-start conditions, timing-chain failure, and engine replacement recommendations. I am filing because this appears to be an ongoing safety risk involving oil consumption without adequate warning, timing-chain/timing-guide failure, internal contamination, and sudden engine failure. I request NHTSA review this issue for investigation or recall expansion before this failure mode causes a preventable serious crash, injury, or fatality. The vehicle was inspected by a GMC dealer and remains unrepaired.

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After vehicle acting like it isnt getting power and trying to die, I pulled into a gas station and turned it off. When I went to restart it, the vehicle kept turning over and over automatically not wanting to start and the engine light came on. I let it sit for about 5 minutes and tried again. It did same thing. I tried a 3rd time pushing the gas pedal and it finally started. I made it home 2 miles away. Turned the car off and tried starting it again with same issues.

See attached document for complaint.

I bought this car and the mileage said 120k, but the title says when it was tagged 157k. The car has been tampered with and the some of the lights for the car on the dash are missing, such as the check engine light. Also, it misses so bad that it will die at times.

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Took dealer 3/26 for sam issue engine power reduced after already cause me hit curb. Got it out 4/1/26 now 4/5/26 it happened again same codes after they claimed they fixed it. Also keep having emergency services come on a caused my dashboard out. My issues is car keeps stalling losing power. Same codes as week ago after dealer fix. Also 4 time took for noises in my car from passenger side. They keep telling me they can’t replicate it, but you can clearly see where the door is not lined up. This has been going on for over 30,000 miles for that. Like some of these issues have been going on since the 36,000 but now I’m having issues where I’m losing power like this is insane all before 60,000 miles which I’m about to hit. It’s gonna end up getting me killed on the interstate. My VIN also says it’s fwd it’s awd at4 . Called dealer said only to update software clearly not the issue. My doors are off and they have refused to fix those for over 30,000 miles now. It won’t let me attach any pics for some reason I’ve tried since yesterday.

Oil consumption, causing high pressure furl pump to clog. It also causes catalytic converter to clog. No warning of oil loss. Causing stalling out while driving. Caused the engine to seize. New engine replaced and still same problem s.

While driving the vehicle became extremely difficult to stop I was advised that the vacuum booster pump was broken and it needed to be replaced. This was first completed 09/24/25 by gateway tire and service center. I was advised that there was a service bulletin for the issue. Then I have had the same thing happen and I returned the vehicle to the same repair shop and I was advised that the vacuum booster pump was broken and it caused the exhaust camshaft to break, as well as the timing was out. The shop had to replace several things in order to repair and I was responsible for the cost. There was no warning before either of the incidents.

Have had to replace the vvt solenoids several times within a year spam. Had to replace the rear main seal because it blew out due to carbon build up. Having issues with excessive oil consumption. Now the vehicle just started with: going from a stop position to accelerating at low speeds the vehicle stalls and dies. I want gm to take accountability and fix this issue as it is a safety issue to myself and everyone on the road.

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The contact owns a 2018 GMC Terrain denali. The contact stated while the contact's daughter was driving, the brake pedal was depressed, however the vehicle failed to stop as intended. In addition, the contact stated that the brake pedal was unusually hard when depressed. The vehicle was taken to the dealer where the vehicle was purchased. The contact stated that the service brake vacuum pump failed while the vehicle was at the dealer. The vehicle was diagnosed with a failed service brake vacuum pump and a failed engine. The contact was informed that the service brake vacuum pump, the cam shaft and the engine needed to be replaced. The vehicle was repaired. The contact stated that the failure was a known failure of the vehicle. The manufacturer was not made aware of the failure. The failure mileage was approximately 260,000.

Vacuum pump exploded into camshaft and engine area, causing me to lose brakes completely on the highway. Costly repairs to clear out metal shrapnel and replace camshaft.

The contact owns a 2023 GMC Terrain. The contact stated that while driving on several occasions at various speeds, the check engine warning light illuminated, the message "engine power reduced" was displayed, and the vehicle lost power. The vehicle stalled on three separate occasions. The vehicle was able to restart each time after approximately 15 minutes of waiting, but the vehicle failed to accelerate above 40 mph. The vehicle was taken to a dealer and dtc: p228c, p0089, and p006c were retrieved, and the contact was informed that the fuel pump and fuel injectors needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was unknown.

I was driving 55 miles an hour on an expressway. And suddenly my truck just shut off. The brake became very hard unable to break very scary situation for me and my children. Engine power was reduced and would not start, many errors came up. The vacuum pump failed, which also caused the cam shafts to fail. The vacuum pump exploded into pieces and sent metal into my engine.

The turbo went completely out at around 105k miles while I was driving to work. I had to coast into a repair shop because it was smoking and wouldn’t go over 20mph and then have it towed to the place that repaired it. Since then, the transmission is having trouble shifting gears. The car struggles to accelerate and I have to go abnormally slow after coming to a complete stop in order for the car to get into gear. The onstar diagnostic says everything is fine but it is clearly not fine.

My vehicle started turning off suddenly when stopped and then when starting to move. I replaced my rear seal. A week later, I have oil in my timing and my engine no longer works. I have had it checked by a shop. No warning was given. I have my oil checked regularly and changed on time. I had a car full of people, adults and children, in rush hour traffic. The car is sitting in my driveway as I will need to negotiate with the lender on money owed. I am currently without a safe vehicle to drive, and I need that as I am a caregiver and home aid.

Check engine light is coming on, indicating reduced engine power. Took vehicle to GMC dealer and they advised that the repair shop was getting assistance from the GMC tech line to update a module to correct the issues. I was informed today that the high pressure fuel pump will have to be replaced, along with a hose or pipe to correct the issue. The vehicle has 57k miles on it. Upon researching the issue, I found that this has been a persistent issue with this model vehicle, dating back to 2020. It appears that it has not been resolved and the vehicles could stall or stop at any time. There is currently a class action lawsuit pending on this issue. Please help, this is dangerous.

While driving several times smelt gas and car cut out engine came on and car stopped mid driving multiple times. Says they replaced fuel pump reset car etc.

I was driving the car on 12-22-25 I lost power my car died on i94. Battery died the dearlship couldnt get the code. Got the car back on 12-26-25. Engine light came on carrie GMC replaced battery . Car back on 12-29-25. . Engine light back on 12-31-25 car back on 1-8-26 replacled catalytic conveerted and oxy sensor. 2-20-26 driving on 1-94 lost engine power car back on 2-25 feul pump and feul line. Drove 300 miles engine light back on. Back to currie GMC on 2-26-26 untill 3-2-26 replacred heated oxygen sensor . 3-6-26 replaced catelytic converter and oxyger sensor for the second time.