2021 GMC Acadia: What to check before buying

Engines quit without warning when the fuel pump control module fails, either at startup or while driving, and some owners need repeat replacements. Early failures appear near 8,100 miles. Other reports describe the instrument cluster and dashboard going black at speed, taking the speedometer and driver aids with it. Backup cameras stop working, infotainment screens show SD card errors, key fobs go undetected and lock owners out, and the electronic parking brake sets on its own. Two complaints involve crashes, one with an injury, and one links a crash to the backup camera.

Stalling at speed is the dominant failure. The engine sputters or bucks and then dies, often with no warning light, at highway speeds or in traffic. Dealers usually trace it to the fuel pump control module, and several owners have had it replaced more than once. After a stall the shifter often will not move into neutral and the parking brake may not release, so cars sit stranded in live lanes until a flatbed arrives. Reported failures range from under 10k miles to 46,000. Owners also report the replacement part on national backorder.

Loss of power while driving, followed by a stall and a no-restart, describes every report. The fault is traced to the fuel pump control module or fuel pump module, sometimes with code P023F. Some cars give no warning, while others light the check engine lamp first. Failures happen in traffic and at highway speed, including one near-miss with a tractor trailer. Mileage in one report is 36,970. Owners also report the replacement part on backorder, which keeps cars off the road.

Transmission slipping, shuddering and harsh shifts make up most of these reports. Owners feel slipping on acceleration, jerks between gears, shudder at low speed, and engine revving without power. Some cars drop into neutral or stall, and one complaint is crash-related. Problems begin as early as under 9000 miles. Dealers often find no fault, and a fluid change under a service bulletin did not fix one car. A second group of complaints describes a cooling fan that keeps running after shutoff, a temperature gauge stuck on cold, and a reduced driver or steering assist warning.

Front brakes grind and squeal, usually when cold or after sitting overnight, even on low-mileage cars, and repeat dealer visits often end without a fix. More serious reports describe sudden loss of braking. Causes include front brake hoses rubbing against the CV axle or drive shaft until they leak or tear, a failed vacuum pump, and a leaking ABS modulator. Pedals that sink to the floor and fluid on the driveway are warning signs. Other complaints describe automatic braking activating for no reason and the parking brake engaging while driving. One complaint involves a crash.

Thermostat failures lead the list. They set codes, trigger a reduced steering assist message, and leave the cooling fan running after shutoff. Some owners also need a radiator or oil cooler, with one corroded radiator leaking at around 32,175 miles. A loud buzz or rattle from the front muffler or resonator, felt through the passenger floor around 2,000 to 2,500 rpm, is also common, and owners cite a service bulletin for it. Catalytic converters crack and get replaced repeatedly. Crankcase moisture codes and fuel pump module stalls round out the reports.

A "Steering Assist Is Reduced" warning dominates. It usually arrives with a temperature gauge stuck on cold, loss of heat or AC, and a loud cooling fan that keeps running after the engine is off. Owners report that disconnecting the battery clears it temporarily. Diagnoses point to a failed thermostat or coolant temperature sensor and module communication codes. Some owners have the problem return several times. Less often, the steering turns suddenly stiff on the highway, the car pulls to one side, or a stall brings on the warning.

A "Service Safety Restraint System" warning comes on and goes off at random while driving, sometimes within days of delivery. Dealers replace the airbag control module or work on seat belt tensioners, but the light often comes back, and repairs can take two weeks. Repeat failures appear between 3,741 and 16,000 miles. A warning light can mean the airbags may not deploy. One crash-related complaint with an injury describes the front airbags deploying in a low-speed parking lot impact and breaking the driver's arm.

Few reports, but they vary. One crash-related complaint describes the accelerator pedal sticking to the floor while reversing, putting the car into a garage wall at about 2,500 miles. Another describes the transmission slipping near 8900 miles, with dark, muddy fluid returning within 100 miles of a fluid change and the dealer planning to take the transmission apart. A third describes brake trouble after a vacuum pump failure.