2020 GMC Sierra Denali Engine Problems
- Complaints
- 6about this part
- Share
- 55%of 11 total for the year
- Median mileage
- 20,000miles
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
NHTSA recorded 6 complaints about the engine of the 2020 GMC Sierra Denali, 55% of the 11 complaints for this model year. Where a mileage was given, the median is 20,000 miles.
Fewer than 15 complaints name this part, so treat the figures as a rough indication only.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“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, filed 2020-10, 2,200 miles“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, filed 2020-10, 350 miles“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, filed 2026-06, 98,500 miles“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. …”
NHTSA complaint #11763621, filed 2026-09, 25,000 milesRelated service bulletins
- 11024330Sep 6, 2025This technical bulletin provides a procedure to replace the camshaft actuator magnet to correct customer concerns of engine related shudder.
- 11026017Jun 5, 2025This service bulletin provides information on replacing the intake manifold when the engine is replaced after severe internal engine damage.
- 11024486May 16, 2025This bulletin advises the tech to inspect deeper into what may be to main cause of an engine failure.
- 11024485May 15, 2025The service bulletin advises the tech of a normal transmission shift condition and the delay in throttle response when the throttle plate is opened rapidly and advises the…
- 11020254May 7, 2025This service bulletin provides information to dealership personnel for new vehicles with less than 1,000 miles that may not pass California smog inspection or smog inspection in…
- 11019503Apr 18, 2025This warranty administration bulletin provides policy information on vehicles outside of a California Emissions State who move to and register their vehicle in a California…
- 11017263Mar 25, 2025This bulletin advises the technician to flush the cooling system multiple times if oil has been found in the cooling system and replace the parts that may be contaminated due to…
- 11016942Mar 4, 2025This bulletin advises the technician to flush the cooling system multiple times if oil has been found in the cooling system and replace the parts that may be contaminated due to…
- 11014230Jan 31, 2025This bulletin advises the dealers to maintain the vehicle stock on hand by doing a full inspection on the vehicles before being sold (prepping) to the customer.
- 11014233Jan 30, 2025This service bulletin provides service information to technicians on guidelines to replace Oil Cooler, Oil Cooler Lines and Oil Tank if the engine was replaced where large…
Engine: other model years
Other parts of the 2020 GMC Sierra Denali
2 complaintsForward collision avoidance
2 complaintsElectrical system
1 complaintsEngine cooling
1 complaints
← All problems reported for the 2020 GMC Sierra Denali
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology