2020 Chevrolet Suburban: What to check before buying

Transmission failure is the main pattern, usually close to 100,000 miles. The transmission slips, RPMs stop matching road speed, and a whine or shudder builds. Then the SUV won't accelerate past 40 to 50 mph or stops moving on the highway. Warning lights often stay off, so dealers can miss the fault. Repairs run about $7000, and a torque converter replacement did not cure one shudder. Other reports cover cold-start lifter ticking and grinding differentials with metal shavings. One front differential was on back order.

Lifters collapse and camshafts fail on the 6.2-liter V8, with failures reported near 95,000 miles. Warning signs include cold-start knocking or ticking, misfires, stuttering under acceleration, and violent shaking on only five cylinders. The usual fix is a full engine replacement, and quotes run as high as $10-20,000. One owner waited four months for a replacement engine. In another case, a vehicle caught fire on the highway during a dealer test drive after getting a new engine, and it was a total loss. Separate reports cite a leaking fuel injector diluting the oil and a burst water pump.

Intermittent electrical faults switch systems off and on by themselves. Power steering cuts out, the wipers start on their own, and the instrument cluster goes black. One dealer fixed this under a technical service bulletin. A mechanic blamed one engine replacement at 120,000 miles on a degraded fuel injector wiring harness and a faulty sensor that shifts the engine between V8 and V6 modes. One complaint is odometer fraud: a private-sale vehicle sold with 88,000 miles had 252,000 on record.

Power steering assist cuts out without warning. The wheel goes firm while driving, sometimes followed by a Service Power Steering message. Some startups knock out steering assist, stability control, the speedometer and tachometer, and reverse gear, leaving only first gear. These faults can clear after repeated restarts and then return. Stalling while driving takes power steering and power brakes with it. One owner also describes the front wheels seeming to turn on their own in corners, which is a loss-of-control risk on wet roads.

In one crash, no airbags deployed when another vehicle traveling about 45 mph hit the driver-side front quarter during a left turn. Separately, a Service Safety Restraint System warning comes and goes as if from an electrical short. The owner notes that the related service bulletin covers only 2021-2023 models, so the 2020 is left out. Only two complaints are on file, but both question whether the restraint system will work when needed.

With no warning light or message, the brake pedal sinks to the floor and the vehicle will not stop. Pumping the pedal does not help. The dealer fix was a new master cylinder, brake booster, and vacuum pump. A crash-related report describes brakes that stiffen and need heavy effort to press. It came alongside a grinding starter, no-start episodes, and stalling right after startup, and repeated dealer visits did not fix it.

Adaptive cruise control reacts late when the vehicle ahead slows, so the driver has to brake hard to avoid a collision. Above 65 mph it leaves too little following distance, and the problem shows up from the first long trip. The other complaint filed here is really an engine failure: clicking and knocking on the interstate, then a complete loss of throttle within minutes. The dealer called it catastrophic engine failure. Steering and brakes kept working long enough to reach the shoulder.

Most of what is filed here describes engine and wiring trouble rather than suspension wear. One vehicle needed two engine replacements by 70,000 miles, with failures at high speed. It also has a recurring wiring harness fault that cuts power steering while driving, which the dealer has not fixed. The one true driveline complaint describes a jolt from the right front while accelerating above 50 mph with automatic four-wheel drive engaged. It has persisted since purchase.