2019 GMC Terrain problems

Filed Oct 23, 2026 · Transmission · IL

Transmission leak caused but start and stop accumulator

Filed Oct 13, 2026 · Brakes, Engine · CA

VIN: [XXX] Mileage: Approximately 103,576 Incident location: [XXX] Safety Complaint: While my wife was driving our 2019 GMC Terrain into a shopping center parking lot, the vehicle suddenly experienced a severe loss of braking assistance. The brake pedal became extremely stiff and difficult to depress, and she was barely able to slow the vehicle. This occurred unexpectedly while the engine continued running, creating a serious risk of a collision. Following the incident, I inspected the vehicle using an OBD-II diagnostic scanner, which identified diagnostic trouble code P0016 (crankshaft/camshaft position correlation). The vehicle also displayed an oil-pressure warning. We subsequently had the vehicle inspected by John's Automotive Care in [XXX] on XXX. During the inspection, the technician discovered a significant amount of metallic debris in the engine oil. The repair facility suspects a mechanical failure of the engine-driven brake vacuum pump, potentially resulting in damage to the engine and lubrication system. The repair facility recommended replacing the mechanical vacuum pump and engine oil-pressure switch and performing an oil change. However, the service representative explained that these repairs would not guarantee the engine's continued reliability because the engine was compromised and could fail at any time. We are extremely concerned that a failure involving the brake vacuum pump could cause sudden loss of braking assistance without adequate warning, potentially resulting in a serious accident. We request that the federal safety agency investigate whether this failure represents a safety-related defect affecting the 2019 GMC Terrain and other vehicles equipped with similar engine-driven brake vacuum pump systems. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 24, 2026 · Brakes, Electrical · AR

While driving on an interstate, vehicle became sluggish when accelerating. Took off on exit, engine was reduced to 50% power, attempted to drive to large parking lot, lost brakes, got the vehicle stopped in an intersection, would not shut off, go into neutral. Finally shut off, had to call tow truck, holding up traffic in a busy intersection. Was told it would be just $900 to fully diagnose problem, but it appeared the vacuum pump failed, threw broken metal into engine and now will have to be replaced at my cost. NO advanced warning of any type of problem, no warning lights, etc.

Filed Sep 23, 2026 · Transmission · 60,000 miles · MI

The contact owns a 2019 GMC Terrain. The contact stated that after pulling into a parking lot, the vehicle failed to shift into park. The vehicle was towed to a dealer where the contact was informed that three fault codes were found. The dealer informed the contact that the transmission needed to be disassembled for a full diagnostic test. The vehicle was not repaired. The vehicle was scheduled for the transmission to be disassembled for the diagnostic test. The failure mileage was approximately 60,000.

Filed Sep 17, 2026 · Brakes, Engine · KY

On 9/15/2026, my wife drove her car, a 2019 GMC Terrain, to a doctor's appointment. She reported no known issues with the way the car operated during her drive nor had she or I experienced issues prior to this event. After she finished her appointment, she attempted to start her car and was unable to get the car to start. She also noticed that the brake pedal was stiff and hard to depress. When I arrived, I tried to assist her, thinking that an electrical issue was the fault. However, I was still unable to start the car and I had to have it towed after I couldn't start her car. I had it towed to a mechanic who initially thought the car had a bad starter, however, after attempting to manually turn the engine, he found that the engine was completely seized. He also confirmed that the oil in the car appeared to be without fragments in it and that the oil level was adequate for normal operation. This car is only seven years old, has had routine maintenance, and is about 60 miles over 100,000. No prior issues were noticed before this happened. I'm currently waiting on an engine for the car so we can start using it again.

Filed Sep 4, 2026 · Brakes, Engine · MA

While driving my 2019 GMC Terrain with three children as passengers, the vehicle developed a braking/engine problem. The brake pedal became very hard, and the vehicle subsequently became undrivable and would not start. I received no advance warning through the GMC app indicating that the vacuum pump was failing. The vehicle was towed to a GMC dealership. The dealership diagnosed a failed vacuum pump and advised that the engine requires replacement, with an estimate of approximately $11,238. I purchased this vehicle new. I am very concerned that a vacuum-pump failure can result in reduced brake assist/increased brake-pedal effort and major engine damage without adequate advance warning. Three children were in the vehicle when this occurred, and the sudden change in braking created a serious safety concern for everyone in the vehicle. The vehicle is currently at the GMC dealership. I have requested that relevant parts be preserved and am requesting GM Policy Assistance with the repair.

Filed Aug 21, 2026 · Body, Visibility · NJ

This is the second time I have noticed storm heavy rain that my car is taken on water. We had an extremely heavy rain in June and no windows was left open. I did not know water had gotten into my car for an entire month when I heard a solution sale when I came to a break, what I did realize is that there was condensation buildup is inside of my car, but it was not sure why. After searching, I was able to locate and discover thatI had at least 3 inches of water standing water in my spare tire, section of my trunk. There was also an extreme amount of water on my floors in the back row once I took out my mats, I found there to be mold back there.Still unsure of how t the water got into the car I used my shop vac to suck out the water. We just had an extreme amount of heavy rain again. We are now in August. We just had extremely heavy amounts of rain and once again there’s water in the well trunk of my car where the spare tire is. I actually made sure to sit outside in my car during this heavy rain storm to see where the water was coming from. It appears that the water is coming from the sunroof, which then leaks to the back on the right hand side where the outlet socket is. I watched it dripped down into the back of the trunk into the spare tire well. I do not understand why this issue has not triggered a a recall yet as I’m noticing this is not just with my car. This is apparently the sixth or seventh car that has experienced this issue and GMC has yet to do a recall on it. This is very alarming and concerning God forbid I’m driving to work or I have one of my children in the car during a heavy rain storm and it hits the electrical wires or electrical panel with something else bad happens.

Filed Aug 21, 2026 · Brakes, Electrical · PA

On Saturday, August 15th we were driving on the freeway when with no warning the check engine light came on and the vehicle began to run poorly, and then the vehicle lost electrical power and it became difficult to steer and the brake pedal became stiff, making it difficult to stop and pull over. The vehicle would not start on command but kept running very poorly, it also became impossible to shut the vehicle off until it seized. It was later towed to a local repair shop, and today, Friday August 21st the shop confirmed that the vacuum pump on the brake assist failed and it would need a total engine replacement.

Filed Aug 18, 2026 · Brakes, Engine · NJ

The car’s brakes hardened on the highway, posing a life-threatening danger, right before the engine died. Following a tow to the dealership’s service center, an initial inspection revealed a broken vacuum pump and broken camshaft. The dealership stated that there was evidence that camshaft debris may be scattered throughout the engine. No further inspection has been done at this time due to the probability of major engine damage and/or potential repairs.

Filed Aug 9, 2026 · Brakes, Engine · MI

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."