2020 GMC Sierra Denali

11 complaints on file, page 1 of 1.

1. Filed Sep 14, 2026Failure Sep 14, 202699,000 milesCastroville, TXAdaptive cruise control

   The contact owns a 2020 GMC Sierra Denali. The contact stated that while driving with Adaptive Cruise Control set to 55 MPH, the vehicle suddenly accelerated. The contact depressed the brake pedal to disengage the Adaptive Cruise Control settings, preventing the vehicle from crashing into the vehicle ahead. The contact stated that the failure had occurred while the Adaptive Cruise Control was engaged. The approximate failure mileage was 99,000.

   NHTSA complaint 11764047
2. Filed Sep 11, 2026Failure Jul 11, 202225,000 milesHigh Point, NCEngine

   The contact owned a 2020 GMC Sierra Denali. The contact stated that while the vehicle was parked, there was an abnormal knocking sound coming from the engine compartment. The check engine warning light was intermittently illuminated. The vehicle was taken to a dealer; however, the cause of the failure was not yet determined. The dealer advised the contact to purchase a new vehicle because the engine would eventually need to be replaced. The contact stated that at approximately 3,000 miles, there was an abnormal odor oil burning odor coming from the vehicle. The contact stated that the vehicle was consuming an excessive amount of engine oil and approximately 5 quarts needed to be added between scheduled oil changes. The failure mileage was approximately 25,000.

   NHTSA complaint 11763621
3. Filed Jun 16, 2026Failure May 1, 202598,500 milesEaton, COEngine

   The contact owns a 2020 GMC Sierra 1500 Denali. The contact stated that while parking the vehicle, there was an abnormal grinding sound coming from the engine. There was no warning light illuminated. The local dealer was contacted about the failure; however, the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 98,500.

   NHTSA complaint 11744588
4. Filed Nov 18, 2025Failure Nov 10, 2025190,000 milesGreensboro, NCEngine and engine cooling

   The contact owns a 2020 GMC Sierra Denali. The contact stated that while stopped at a traffic light with the brake pedal depressed, the vehicle shut off unexpectedly. There was no warning light illuminated. The contact made several attempts to restart the vehicle; however, the vehicle failed to restart. Due to the failure, the vehicle was towed to the dealer where a diagnostic test was performed. The contact was later informed that the engine had seized due to engine bearing failure, and the contact was provided an estimate for a new engine. Upon investigation, the contact discovered NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling) and linked the recall to the failure. The manufacturer was notified about the failure and the recall, and the contact was informed that the VIN was not included in the recall. The vehicle was not repaired and remained with the dealer. The failure mileage was approximately 190,000.

   NHTSA complaint 11700178
5. Filed Nov 9, 2023Failure Oct 10, 20226,700 milesJoplin, MOSoftware

   The contact owns a 2020 GMC Sierra Denali. The contact stated while driving 75 MPH, the Adaptive Cruise Control feature became inoperable. The contact stated that when the vehicle got too close to another vehicle, the Adaptive Cruise Control feature failed to activate as designed. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 6,700. The VIN was unavailable.

   NHTSA complaint 11554317
6. Filed Apr 26, 2023Failure Apr 8, 2023Williston, FLStarter assembly

   The contact owns a 2020 GMC Sierra Denali. The contact stated while driving 65 MPH at night, the vehicle stalled and the “Shift to Neutral and Restart Vehicle” message was displayed. The contact was unable to restart the vehicle and was unable to visibly see the roadway. The contact was able to park on the side of the road. The vehicle was not drivable. The contact towed the vehicle to his residence, and then to the local dealer the next day, where the vehicle was diagnosed with needing the starter to be replaced. The vehicle was repaired. The manufacturer had not been informed of the failure. The failure mileage was unknown.

   NHTSA complaint 11519126
7. Filed Nov 23, 2021Failure Jun 1, 202120,000 milesAmmon, IDEngine

   The contact's father owns a 2020 GMC Sierra Denali 3500. The contact stated that while his father was driving at an undisclosed speed, the check engine warning light illuminated. The vehicle was taken to the dealer and diagnosed with a cylinder #1 misfire. The vehicle was repaired; however, the failure recurred. The vehicle was then taken to Wackerli Auto Center (1363 N Holmes Ave, Idaho Falls, ID 83401) on numerous occasions and diagnosed with a faulty sensor. The dealer replaced the sensor; however, the failure recurred. The vehicle was not repaired and remained at the dealer. The manufacturer was made aware of the failure. The failure mileage was approximately 20,000. The VIN was unavailable.

   NHTSA complaint 11441449
8. Filed Apr 7, 2021Failure Aug 15, 20203,000 milesTuscumbia, ALService brakes

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

   NHTSA complaint 11406920
9. Filed Dec 16, 2020Failure Aug 24, 2020Rockport, TXEngine

   KNOCKING COMING FROM ENGINE - NOTICEABLE UNNECESSARY NOISE IN WHICH DEALER CAN NOT FIX THE PROBLEM

   NHTSA complaint 11383781
10. Filed Oct 29, 2020Failure Oct 29, 2020350 milesSoddy Daisy, TNEngine, Service brakes

    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 complaint 11367036
11. Filed Oct 8, 2020Failure Oct 7, 20202,200 milesKentfield, CAEngine

    I NOTICED SEVERAL SPOTS OF OIL ON MY DRIVEWAY, I THEN INSPECTED THE UNDERSIDE OF THE ENGINE (L5P) AND NOTICED OIL DRIPPING FROM SEVERAL BOLTS AND LINES. MY VEHICLE, A 2020 2500HD DENALI DIESEL, HAS ONLY 2,200 MILES ON IT FROM NORMAL HIGHWAY DRIVING.

    NHTSA complaint 11363419