2025 GMC Sierra 1500: What to check before buying

Catastrophic engine failure is the main pattern, often very early. Trucks show a "Reduced acceleration" warning or drop into limp mode, then knock, lose oil pressure, shed metal into the oil, or seize. Several failures happen between 1,185 and 5,200 miles. Dealers often point to a faulty thrust bearing covered by TSB 25-NA-307 and replace the whole engine. Some trucks stall in traffic or lose power on the interstate with no safe place to pull off. Less common reports cover a cracked valve cover leaking oil, a chirp from the 6.2L, and diesel DEF warnings that count down fast while towing.

Engines knock or stall without warning. In one case, the dealer found a failed thermostat coolant housing and a long list of trouble codes, but the knocking was still there after the repair. In another, the truck stalled at a light, would not restart, and the engine was found to be seized at about 21,100 miles. That owner connects the failure to recall campaign 25V274000.

Harsh shifts followed by sudden power loss are the most common complaint. The truck goes into a protective shutdown mode, steering stiffens, and warning lights fill the dash at speeds up to 70 mph. Other trucks stall and cannot be shifted into Neutral to push them out of traffic, or slow down sharply on cruise control. In one crash, a truck idling in Park shifted into Reverse by itself. Some owners report shudder at 25 to 55 mph or highway vibration that dealers cannot duplicate. One owner reports a failed transmission module at 20,989 miles.

Trucks shift out of Park on their own in two crash reports, one with no one inside. More often, all cabin audio cuts out, which also silences turn signals, collision warnings, and seatbelt chimes. It keeps coming back after repeated dealer repairs. Radio power, home, and steering-wheel buttons stop working. Other reports describe false collision alerts that trigger automatic braking, cameras that shut off once the truck warms up, and a backup camera too dark to use at night. One OnStar module failure turned into weeks of waiting for parts.

The backup camera is almost useless at night. The picture is clear in daylight but goes nearly black in dim areas. Dealers at more than one shop say nothing can be done, and owners report that GMC treats it as normal. A separate report covers the defrost blower dropping to its lowest setting when snow covers the cowl vents. The windshield then fogs or ices up, and the driver has to pull over and clear the vents by hand.

The heated steering wheel gets hot enough to nearly burn. Owners measure temperatures from 119 to 143 degrees Fahrenheit and have no way to pick a lower setting. One more serious report describes a hard shift and loss of acceleration at 65 mph. The truck shut down, steering assist was lost, the brakes went hard, and the truck had to be towed. That fits the transmission shutdown pattern reported under power train.

The backup camera cannot show people or objects at night unless the area is brightly lit. Dealers inspect the camera and report that it works as designed, so no repair is offered. At least one owner added an aftermarket light to back up safely after dark. Both complaints come from new trucks and match the night camera reports filed under visibility and electrical.

The truck can surge forward at parking speeds. If the cruise control toggle on the left steering-wheel spoke gets bumped below 2 mph, cruise engages at a set speed of 15 mph and accelerates. The owner says this can be repeated at will. A separate report describes sudden acceleration with squealing tires after a light tap on the pedal, ending with the truck driving over a cement barrier at about 7,800 miles.