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FaultScore report

2020 GMC Sierra Denali problems

Owners have filed 10 complaints about the 2020 GMC Sierra Denali with NHTSA between 2020 and 2026. The largest single group is the engine & cooling. Across this model's run it ranks 10 of 14 worst.

Read the complaints What breaks Worst years for the GMC Sierra Denali All 2020 cars
B

FaultScore 31/100

Higher is worse. Measured against the other years of the GMC Sierra Denali.

How this is worked out

The numbers

10

Complaints

0

Crashes reported

0

Fires reported

0

Injuries reported

4,850 mi

Median mileage at failure

Half of reported failures happened before this

75%

Failed under 36,000 miles

Inside a typical bumper-to-bumper warranty

What kind of bad

The letter says how bad. This says what kind — whether this year drew an unusual number of complaints, unusually dangerous ones, or failures that arrived unusually early.

Complaint volume 22 vs 50 Severity 0 vs 50 Early failure 100 vs 50
The dashed ring is 50 — the national norm. Further out is worse.
Complaint volume — 22
Against the median year of the GMC Sierra Denali. 50 means typical for this model; 100 means roughly double.
Severity — 0
0% of these complaints involved a crash, fire, injury or death, against a national rate of 9.7%.
Early failure — 100
75% of failures with a mileage on record happened under 36,000 miles, against a national rate of 29%.

How 2020 compares with every other GMC Sierra Denali

Click any bar to open that year's report.

Complaints filed with NHTSA, by model year. Bar colour is the FaultScore grade: A B C D F ungraded

What breaks on a 2020 GMC Sierra Denali

Every complaint is filed against a part. Follow any row for the complaints about that part alone.

Engine & Cooling 6 60.0%

Median failure at 20,000 miles

Brakes 2 20.0%

Median failure at 1,675 miles

Driver Assist & Collision Avoidance 1 10.0%

Median failure at 6,700 miles

Electrical System 1 10.0%

When it fails

Odometer readings owners gave when they filed. About half of all complaints include one.

Under 1,000 miles 2 25.0%
1,000 – 9,999 miles 3 37.5%
10,000 – 24,999 miles 1 12.5%
75,000 – 99,999 miles 1 12.5%
150,000+ miles 1 12.5%

When owners complained

A spike years after the car went on sale usually means a part wearing out on schedule across the whole fleet — the kind of pattern no single owner can see from inside their own car.

Oct 2020 peak 3 Jun 2026

The most recent complaints

In the owners' own words, exactly as filed with NHTSA.

at 98,500 miles Eaton, CO

ENGINE

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 — an unverified report by a vehicle owner.

at 190,000 miles Greensboro, NC

ENGINE 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 — an unverified report by a vehicle owner.

at 6,700 miles Joplin, MO

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL:SOFTWARE

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 — an unverified report by a vehicle owner.

Williston, FL

ELECTRICAL SYSTEM:STARTER 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 — an unverified report by a vehicle owner.

at 20,000 miles Ammon, ID

ENGINE

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 — an unverified report by a vehicle owner.

at 3,000 miles Tuscumbia, AL

SERVICE BRAKES

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

NHTSA complaint #11406920 — an unverified report by a vehicle owner.

Rockport, TX

ENGINE

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

NHTSA complaint #11383781 — an unverified report by a vehicle owner.

at 350 miles Soddy Daisy, TN

ENGINE

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 — an unverified report by a vehicle owner.

at 350 miles Soddy Daisy, TN

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 — an unverified report by a vehicle owner.

at 2,200 miles Kentfield, CA

ENGINE

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 — an unverified report by a vehicle owner.