GMC Complaints

Leaking transmission fluid at 7,000 miles. Technicians noticed during routine oil change at dealership.

When trying to put car in park a "shift to park" notice appears on dashboard not allowing the car to be turned off. It takes multiple attemps be able to get the car into park and turn OFF. This has been an ongoing problem for several years and reported to the dealer. To date the dealer tells me there is nothing wrong with the car. Battery has been changed multiple times.

My family drove from [XXX] to [XXX]. Upon arrival check engine light came on, we proceeded to a local shop, by the time we arrive check engine light was flashing and engine was knocking and was clearly malfunctioning. Shop owner recommended we transport the vehicle back home as service shops in the area were experiencing high volume and parts shortages. We had vehicle towed to a local shop in [XXX]. The engine is giving diagnostic codes P0300, P050D, [XXX] with internal knocking and tapping. Vehicle has been kept current on all oil changes and has no external leaks. GMC wants at least $12,000 to replace the engine. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

[Symptom & Safety Hazard] While driving my 2020 GMC Acadia 3.6L V6, the Driver Information Center displayed the warning: "Steering Assist Reduced, Drive With Care" (SARDWC). Steering effort increased abruptly, the engine temperature gauge dropped to cold/zero, and the HVAC system lost air-conditioning function. The warning and reduction in steering assist presented a safety hazard and increased the risk of a crash. [Diagnostic Findings] Vehicle diagnostics identified DTC P0128 - Engine Coolant Temperature Below Thermostat Regulating Temperature. A GMC Certified Dealer technician diagnosed a failed engine coolant thermostat housing assembly. [Manufacturer Information] GM documentation links DTC P0128 and invalid engine coolant temperature signals to the "SARDWC" condition. GM Bulletin 17-NA-158 states the “SARDWC” condition is caused by an invalid coolant temperature signal and the steering module relies on coolant temperature information for steering-assist compensation. GM bulletin PIT5967 directs technicians to diagnose and repair DTC P0128 when the warning message is present. In Oct 2025, GM issued N252508350 for 2021 Acadia vehicles equipped with the 3.6L LGX engine due to an engine coolant thermostat condition. My 2020 Acadia is part of the same generation vehicle platform and is equipped with the same 3.6L LGX engine. It experienced the same thermostat-related failure symptoms, including DTC P0128 and the "SARDWC” warning. [Reason for Complaint] I am filing this complaint because a thermostat-related cooling-system failure resulted in a steering-assist warning and reduction in steering assist while the vehicle was being driven. Moreover, GM issued N252508350 for 2021 Acadia vehicles equipped with the 3.6L LGX engine due to the same engine coolant thermostat condition, yet similarly affected 2020 Acadia vehicles are not included. NHTSA should investigate whether additional 2020 vehicles are experiencing the same failure sequence and resulting safety risk.

Vacuum pump failure caused my brakes to lock up and almost caused me to wreck into another vehicle

Transmission causes problems in can be on interstate and be switching lanes and it loses power and wont go takes forever to shift out. It will cut out and you can barely get pulled off side of rd in time. Electrical the battery voltage goes crazy up and down causing vehicle to power surge bad or at night time lights will go out for no reason while driving every now and then you can smell something melting or burning also the engine gets so hot but it's right temperature cooling fan runs constantly even when car is cool.since all the problem with Transmission the suspension is off some how. Its like it's not stable

my rear window defrost turned on when i auto started my pickup. i realized it was on after about a half hour and looked back and my drivers side of the rear sliding window was shattered completely

Cameras go black and become inop randomly. Been in shop multiple times for concern. Software updates have been performed, modules replaced, cables, and now it’s back for the same concern.

Vehicle was filled with a full tank of gas, went to crank the car up to go home from work it acted like it wanted to crank but seemed to be getting no gas. Diagnostic was performed and the fuel pump control module failed. I thank God It did not start because if it did and I just so happen to pull out into traffic and the car just die in the middle of the road I don't think it would of been pretty. Frankly I think it would of be a very dangerous situation. My vehicle was not part of the recall but somehow my vehicle was still affected hopefully GM would look into the 2020 Terrains with the 2.0 engine. Maybe I will be reimbursed.

The vehicle experienced a catastrophic fuel system failure involving the high-pressure fuel pump and related fuel system components. While driving, the engine began stalling and lost power, making the vehicle unsafe to operate. The failed components were replaced during repairs; however, the repair records, photographs, and additional documentation are available for inspection upon request. The failure created a significant safety risk because the vehicle stalled unexpectedly while being driven, resulting in a sudden loss of power. This placed the occupants and surrounding motorists at risk by reducing the driver's ability to safely control the vehicle or move it out of traffic. The problem was confirmed by an independent repair facility, which documented extensive metallic contamination (metal shavings) throughout the fuel system. Photographs and videos taken during the inspections document metallic contamination within the fuel system. From our understanding, cp4 pump failure has been a common issue.