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What 34 owners told NHTSA about the 2020 GMC Yukon Denali Xl 1500

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (34)Transmission & drivetrain (14)Engine (10)Brakes (3)Electrical system (2)Fuel system (2)Backup camera & sensors (1)Driver assistance (1)Electronic Stability Control (esc) (1)Engine & cooling (1)Seat belts (1)

1 of 34 complaints match · Engine & cooling · clear filters

Jan 8, 2026Engine & cooling

The contact owns a 2020 GMC Yukon. The contact stated that while driving at an undisclosed speed, the check engine warning light was illuminated. The vehicle was taken to the residence, the contact exited the vehicle and discovered white smoke coming from the exhaust and started to smell coolant and then discovered that the coolant level was low. The contact added coolant, and the check engine warning light was no longer illuminated. The contact’s husband and son, who were knowledgeable about vehicles, had self-diagnosed the vehicle and determined that the head gasket or the lifters might need to be replaced. The contact stated that the failure had occurred on several occasions and the contact consistently added coolant; however, the check engine warning light was illuminated every 300 miles once again. The contact researched and was made aware of an unknown NHTSA Campaign Number; however, the VIN was not included. The vehicle was taken to an independent mechanic, where it was diagnosed and determined that there was an unknown internal issue with the engine that was possibly associated with coolant leaking into the engine. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 52,000.

NHTSA ODI 11709635

Working with the data? Download all 34 complaints as CSV · fetched from NHTSA July 25, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2020 GMC Yukon Denali Xl 1500 verdict →