2020 Gmc Sierra Denali problems, complaints & recalls
Most-reported problem areas: Engine (5) · Service Brakes (2) · Forward Collision Avoidance: Adaptive Cruise Control:software (1)
🧭 Reliability snapshot
Compared against other Gmc Sierra Denali model years — complaint volume vs the model's median year, recalls and severity. How we score →
Safety recalls (0)
No recalls on record for this model year (campaigns announced since 2010).
Service bulletins (359)
Technical service bulletins are repair instructions manufacturers send dealers for known issues. Unlike recalls, the fix is not automatically free — but naming the bulletin at the service desk can save diagnosis time and support goodwill repairs.
Unknown Or Other 2026-09-26 · PIT5698F · Service Bulletin/Repair Instructions
this pi provides diagnostics tips on how the lin bus works and how to diagnosis it.
Unknown Or Other 2026-09-04 · PIP4902W · Service Bulletin/Repair Instructions
this preliminary information advises a dealer on how to email gds2 session logs into technical assistance.
Unknown Or Other 2026-07-21 · PIT5099J · Service Bulletin/Repair Instructions
pi to help diagnose a/c concern
Unknown Or Other 2026-04-01 · PIT3271Q · Service Bulletin/Repair Instructions
this preliminary information communicates information about how to determine if a wheel and tires size change is available.
Unknown Or Other 2026-03-09 · PIP6104 · Service Bulletin/Repair Instructions
this preliminary information communicates the steps on how to save a gds2 session log and upload to a technical assistance case in cx connect.
Unknown Or Other 2026-03-09 · PIP4902V · Service Bulletin/Repair Instructions
this preliminary information advises a dealer on how to email gds2 session logs into technical assistance.
Showing the 6 most recent of 359 bulletins. Search all of them free at nhtsa.gov.
What owners report
2026-09-14 · Forward Collision Avoidance: Adaptive Cruise Control · 99,000 mi“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 o…”
2026-09-11 · Engine · 25,000 mi“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 …”
2026-06-16 · Engine · 98,500 mi“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 failu…”
2025-11-18 · Engine And Engine Cooling · 190,000 mi“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 …”
2023-11-09 · Forward Collision Avoidance: Adaptive Cruise Control:software · 6,700 mi“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…”
2023-04-26 · 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 driv…”
2021-11-23 · Engine · 20,000 mi“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 wacker…”
2021-04-07 · Service Brakes · 3,000 mi“brakes squeak. started about 3000 miles. i have complained to dealer several times.…”
2020-12-16 · Engine“knocking coming from engine - noticeable unnecessary noise in which dealer can not fix the problem…”
2020-10-29 · Service Brakes · 350 mi“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…”
Excerpts of consumer complaints filed with NHTSA, lightly truncated. They are owner statements, not verified findings.