2018 Chevrolet Tahoe: What to check before buying

The transmission slips, hesitates, bounces rpm at steady speed, or stops pulling entirely, often with no warning light. Some trucks overheat the transmission into limp mode, shake hard, or stall and shut off in traffic. Reported failures cluster from about 80,000 to 110,000 miles, and repeat failures after repair appear. A torque converter contaminated with metal is one diagnosis. Collapsed lifters that damage the camshaft also show up, with one repair quoted at $7,100. Sudden power loss on highways is the main safety risk.

Brake assist fades and the pedal turns hard, so the SUV takes longer to stop. A failed brake vacuum pump is the usual diagnosis, with failures near 84,000 to 92,104 miles. Service Brake Assist warnings, a vibrating pedal, and a ticking noise come with it. Owners often find their VIN is left out of the recall or special coverage. Two reports involve crashes, one with an injury, including a case where forward automatic braking never engaged. Some trucks also pull hard to one side under braking while showing a trailer brake failure message.

Lifter failures destroy the camshaft and lead to full engine replacement, with no warning lights before the truck loses power. Engine failures are reported anywhere from 22,949 to 83,000 miles, often with a stall or sudden power loss on the highway. A flashing check engine light with misfires on several cylinders is another pattern. Several filings here actually describe transmission failure, including one costly combined engine and transmission repair just past warranty. Repeat fuel pump failures and A/C condenser weld cracks also appear.

Valve train failure is the pattern here. The engine rattles and knocks at startup or abruptly loses power at highway speed with the check engine light on. Diagnoses name failed lifters, the camshaft, and the valve train, with failures around 90,000 and 104,163 miles. Back-ordered parts delay repairs. Owners say their VINs are not included in recall campaign 25V274000 even though the symptoms match.

A Service Trailer Brake System warning with a constant chime is the most common fault, even on trucks that have never towed. In some cases the SUV will not start or slows down while the message is showing. Dealers point to a faulty harness or body control module, and repairs sometimes fail to stick. Other reports describe the whole vehicle losing electrical power while running, a passenger window that rolls back down, a power tailgate that keeps closing on a person, and a grainy backup camera at night.

Power steering assist cuts out without warning and a Steering Assist Is Reduced message appears. The wheel becomes very stiff, sometimes in the middle of a turn at road speed. It often happens at startup and may clear after the truck sits for a while. Diagnoses vary. Some point to a weak battery or a bad ground cable, others to a failed electric steering gear. Failures show up on low-mileage trucks and on ones past 120,000 miles. Owners outside the special coverage report paying over $2,000 and waiting weeks because of a part shortage.

A fuel smell in the cabin and garage comes from leaking fuel injector seals, which a mechanic called a known issue tied to a 2019 bulletin. Another report describes a fuel gauge dropping to empty on a full tank, then the engine shutting off while driving on both highways and city streets. A failed fuel pressure sensor was the diagnosis there. One owner also reports the engine revving on its own with the foot off the gas.

The brakes apply by themselves and stay stuck, sometimes at 60 mph on the highway. It tends to follow activation of forward collision braking or hill assist, with the ABS light on. Earlier symptoms include a sticking caliper that sends smoke from the wheel, and an ABS sensor replacement does not fix it. A separate report says the brake pedal sits too close to the driver compared with the gas pedal, so the foot can get caught between them.

IntelliBeam headlight assemblies fail, and replacement parts are hard to find. One owner waited 2 months because no dealer had the part in stock. The other report covers the rear lighting. The backup lights do not light up enough at night in the rain, so the backup camera image shows almost nothing.