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What 9 owners told NHTSA about the 2020 GMC Sierra Denali

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 (9)Engine (5)Brakes (2)Driver assistance (1)Electrical system (1)Engine & cooling (1)

2 of 9 complaints match · Brakes · clear filters

Apr 7, 2021Brakes

BRAKES SQUEAK. STARTED ABOUT 3000 MILES. I HAVE COMPLAINED TO DEALER SEVERAL TIMES.

NHTSA ODI 11406920

Oct 29, 2020BrakesEngine

TWO ISSUES BROKEN VALVE SPRING CAUSED ENGINE TO SHUT DOWN, SECOND SERVICE BRAKE, BRAKE FAILURE LIGHT, SERVICE ESC, SERVICE TRAILER BRAKE MESSAGES CAUSING BRAKE FAILURE

NHTSA ODI 11367036

Working with the data? Download all 9 complaints as CSV · fetched from NHTSA July 19, 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 Sierra Denali verdict →