Total Complaints
9 filings
GMC SIERRA DENALI · model year
9 NHTSA complaints for this specific cohort.
NHTSA overall rating
Not crash-tested
New Car Assessment Program
The 2020GMCSIERRA DENALI carries 9 consumer safety complaints in NHTSA's Office of Defects Investigation database for this specific model-year cohort. Within that volume, owners reported 0 crashes, 0 fires, 0 injuries, and 0 fatalities. No NCAP 5-star crash-test rating is available for this model year in the federal database.
Component-level analysis is where model-year complaints become actionable: the top complaint category for the 2020 SIERRA DENALI is engine with 4 filings, followed by service brakes (2) and electrical system:starter assembly (1). Concentration in one or two component groups is the classic signature of a systemic defect; a flat distribution usually reflects normal aging, warranty complaints, or isolated build-plant variability.
NHTSA currently has 2 investigation files overlapping the 2020 SIERRA DENALI. Owners comparing this cohort against neighboring years should pair the counters above with the complaint-by-year trend on the parent model page — a spike in a single year often tracks to a platform refresh, a new transmission supplier, or an updated ECU calibration. Use the related-complaint feed below to read raw owner narratives before deciding whether any pattern here affects your specific use case.
Total Complaints
9 filings
Crashes Reported
0 reports
Source
NHTSA ODI
Federal complaints database
At or below the fleet median complaint volume.
| Component | Count |
|---|---|
| ENGINE | 4 |
| SERVICE BRAKES | 2 |
| ELECTRICAL SYSTEM:STARTER ASSEMBLY | 1 |
| FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL:SOFTWARE | 1 |
| ENGINE AND ENGINE COOLING | 1 |
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.
Mileage: 190,000
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.
Mileage: 6,700
The contact owns a 2020 GMC Sierra Denali. The contact stated while driving 65 MPH at night, the vehicle stalled and the âShift to Neutral and Restart Vehicleâ 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.
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.
Mileage: 20,000
BRAKES SQUEAK. STARTED ABOUT 3000 MILES. I HAVE COMPLAINED TO DEALER SEVERAL TIMES.
Mileage: 3,000
KNOCKING COMING FROM ENGINE - NOTICEABLE UNNECESSARY NOISE IN WHICH DEALER CAN NOT FIX THE PROBLEM
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
Mileage: 350
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
Mileage: 350
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.
Mileage: 2,200
Data as of 2025. Sources: NHTSA Office of Defects Investigation (ODI) complaints database, NHTSA recall campaign API, NHTSA NCAP crash-test ratings, and NHTSA FARS for fatality cross-reference.
Read our methodology — how this data is sourced, computed, and verified.