2020 GMC Sierra engine problems
260 of the 479 complaints owners filed with NHTSA about the 2020 GMC Sierra name the engine (NHTSA’s “Engine” heading — the engine and its cooling system). Filed under the same heading: 631 manufacturer bulletins, 2 NHTSA investigations. Every figure below is a document in a federal file, linked; none is a failure rate, and none is a verdict on any one car.
What owners filed about the engine
Source: NHTSA complaint database3 of the 260 reports a crash · 1 a fire · 0 injuries. Self-reported, unverified.
Filed per year: 2020: 11 · 2021: 10 · 2022: 3 · 2023: 4 · 2024: 9 · 2025: 128 · 2026: 95
Half of the 63 owners who gave an odometer reading reported the engine problem between 31,000 and 93,000 miles. A median of reports, not the life of a part.
479 complaints in all about the 2020 GMC Sierra, 95 filed in 2026. The whole picture, every system →
Counts are owner reports to NHTSA, not verified defects, and scale with how many of these were sold; nothing here is a rate. NHTSA groups complaints coarsely, so “Engine” means the same area of the vehicle, not one fault.
Across model years: GMC Sierra engine problems, every year on file →
In owners’ own words
Source: NHTSA complaint databaseFiled with NHTSA by the people who own these cars, about the engine. Quoted as written, with anything identifying removed; unverified reports — what was said, not a finding that it was true.
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 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 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.
A very strong "ammonia" odor comes into the cabin. This happens when the DEF fluid is going into the exhaust system for the regen process. The odor makes people inside nauseous and dizzy. Must open widows or stop and get out of the vehicle. Our Gmc dealer can find no codes or problems with the exhaust system.
The contact owns a 2020 GMC Sierra 1500. The contact stated that shortly after refueling while driving under 15 MPH, the check engine and service emissions warning light illuminated. The contact stated that an unknown reset was performed related to TSB: 10173675 (Engine). The vehicle was not yet fully repaired.
What is on file about the engine
Source: NHTSA recalls, investigations and manufacturer communicationsNHTSA investigations
- EA25007 Loss of motive power due to engine failureopened Oct 23, 2025 · open
- The Office of Defects Investigation (ODI) has received 1,157 reports of engine bearing failure failures in the L87 6.2L engine produced by General Motors (GM). Of the 1,157 reports received, 173 are outside of the scope of recall 25V-274. These engines are installed in Model Years (MY) 2019–2024 Chevrolet Silverado 1500 and GMC Sierra 1500, and 2021-2024MY Chevrolet Suburban and Tahoe, GMC Yukon/Y…
- PE25001 Loss of motive power due to engine failureopened Jan 16, 2025 · closed Oct 23, 2025
- On January 16, 2025, the Office of Defects Investigation (ODI) opened Preliminary Evaluation PE25001 after receiving complaints and field reports concerning engine failures in MY2019-2024 GM’s full-size truck and SUV T1XX platform equipped with the L87 6.2L V8 engine. These complainants alleged engine bearing failures resulting in knocking and growling noises from the engine’s bottom end and in so…
631 manufacturer bulletins filed under this heading
The 0 newest are listed; every one is on the model year’s page. Quote the document number at a service desk — it is a diagnosis the maker has already written down.
Trouble codes named on this system
P12A6 P0300 P0442 P0455 P2463 P0107 P0308 P0201
Codes a bulletin or an owner’s complaint about the 2020 GMC Sierra names on this model year; a code with a record of its own links it.
Other systems with a record on the 2020 GMC Sierra
Source: the same files- transmission and drivetrain problems 97 complaints
- electrical problems 81 complaints
- brake problems 55 complaints
Common questions
Source: NHTSA complaint database, recalls and manufacturer communicationsAre engine problems common on the 2020 GMC Sierra?
They are documented: NHTSA holds 260 owner complaints naming the engine on this model year (54% of everything owners filed about it), and 631 manufacturer bulletins, 2 NHTSA investigations are filed under the same heading. Whether it is a problem on one particular car is a diagnosis, not a count, and a count says nothing about how many were sold.
Is there a recall for the engine on the 2020 GMC Sierra?
No recall campaign is filed under this heading for this model year (there are 12 filed under other headings). A bulletin is not a recall: it carries no federal duty to repair for free.
When do engine problems show up on the 2020 GMC Sierra?
Owners who gave an odometer reading reported it at a median of 64,298 miles; half of them between 31,000 and 93,000. That is when reports cluster, not the life of a part.
What does NHTSA's "Engine" heading cover?
The engine and its cooling system. Owners choose the heading when they file, so it says which area of the vehicle the complaint is about, not which part failed.