The quietest year we cover for this truck — 34 complaints — but the ones that exist are transmissions, and parts have been scarce.

This is the finding a 2020 buyer is least likely to anticipate, and it comes straight from the file. "Severe transmission shuttering destroyed my transmission and I need a new one … Purchased car Feb 2025, brought it in to local auto shop November 2025 and they could not get a transmission for months. They stated one was set to be delivered by GMC Feb 6th 2026 and the day before arrival GMC called them saying it was back on back order. Called the dealership in April 2026 and they stated they were not backordered. Had vehicle transferred to dealership service center and they say it's still on national back order with no ETA. I have been waiting for over 6 MONTHS." A gen-four Denali owner adds the same problem from the rebuild side: "there wasn't a lot of availability for rebuilding 8L90s for the Yukon." If a 2020 needs a transmission, budget for the time as well as the money.

Recall 19V837 covers certain 2020 Escalade, Escalade ESV, Camaro, Silverado 1500, Suburban, Tahoe, Sierra 1500, Yukon and Yukon XL vehicles whose "fuel pump may be missing a pressure regulator, allowing for over-pressurization of the fuel system." GM's consequence line: "Over-pressurization can crack the fuel pump and cause leaks, increasing the risk of a fire in the presence of an ignition source." Dealers replace the pump free. This is the most serious of the four campaigns on this model year and it is a parts fix rather than a software update, so it takes a shop visit — check it against the VIN before you buy rather than after.

Recall 26V289 was issued in May 2026 and reaches back to 2015–2020 Yukon, Yukon XL, Suburban, Tahoe and Escalade vehicles with four-wheel or all-wheel drive. "A component missing from the drivetrain transfer case may cause the front and/or rear wheels to lock up without warning to the driver," and GM advises owners not to drive the vehicle until the remedy is done. Dealers inspect and replace the transfer case assembly free. Only 66 vehicles are affected across every year and nameplate combined, so most trucks will not need parts — but the campaign is very recent, completion rates on used vehicles will be low, and one owner in this year's file already reports a transmission failure that locked the wheels and being told his VIN was not included. Owner letters were mailed 18 May 2026.

The cylinder-deactivation problem does not improve in the last year of the generation. One owner reports a "misfire on #6 cylinder. Diagnosis revealed the intake valve is not opening due to collapsed valve lifter." Another paid $6,000 to rebuild the transmission and then found "the lifters in the engine" had gone, with "no warning lights" ever appearing. Separately, two owners describe coolant entering a cylinder — white smoke from the exhaust, coolant level dropping, a check-engine light returning every 300 miles — and one names the GM service bulletin covering it, 20-NA-166, after the dealership disassembled the engine and "found coolant leaking into cylinder six" and quoted a complete engine replacement. Cold-start and listen, and check the coolant reservoir and the oil filler cap.

Two reports in this small file describe the bottom-end failure that GM later recalled on 2021–2024 trucks. "They said the oil pan was leaking and pulled the pan to discover the crank shaft bearings were failing. The vehicle has 53,765 miles at this point. This appears to be the same defect being recalled on the 2022 through 2024 models." And a truck bought used at 79,851 miles that made a loud knocking noise 8,000 miles later: "about a week later they were able to confirm that it was TOTAL BEARING FAILURE. Mileage 88,054 … Total estimate $18,000 … at no time did the 'check engine' light come on or any other warning system activate. Both mechanics were genuinely perplexed." Recall 25V274 and its ten-year coverage begin at model year 2021 and do not reach a 2020.

Recall 21V115 covers Continental tires fitted to a long list of 2020 GM vehicles including the Yukon and Yukon XL. "The affected tires were cured for too long during production," and GM's consequence is specific: "Over cured tires may develop a break in the sidewall resulting in sudden air loss or a belt edge separation which could lead to a tread/belt loss." Dealers inspect and replace as necessary, free. One owner in this year's file had a front tire blow out at 65 mph at 14,900 miles on Continental CrossContact LX Sport rubber. Most 2020s will be on their second or third set of tires by now, which closes the risk — but check whether the campaign was ever completed, and check what is on the truck today.

One well-documented report is worth reading in full because it shows how the smaller engine faults compound. A 2020 Denali bought used developed an intermittent check-engine light on long drives; one shop said the oil pump needed replacing, the dealer diagnosed "an Engine Oil Pressure Control Solenoid stuck in the off position (P06DD)" at $3,584, and an independent replaced the oil pressure valve and sensors instead. The mechanic's advice afterwards is the tell: "change the oil every 3,000 miles, use OEM oil filters, and thicker oil. He also advised me to check the oil every 1,000 [miles] and add as needed. I do have to add oil approximately every 1,500 miles." On a truck this age, a P06DD code or a habit of topping up oil is a reason to look much harder at the bottom end.