GM bulletin 20-NA-084
What it saysThis service bulletin provides information on normal engine characteristics/noise produced by the LIH or LBP engine. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Apr 2, 2025, received Apr 6, 2022, about the engine — 3 documents under this number. It names 15 model years across Chevrolet and Buick (2020–2025). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
One page for every brand it was filed under. Each brand’s bulletins: Chevrolet · Buick.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis service bulletin provides information on normal engine characteristics/noise produced by the LIH or LBP engine.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 20-NA-084 | Service bulletin | Apr 2, 2025 | 11017430 | PDF, 118 KB |
| 20-NA-084 | Service bulletin | Feb 13, 2024 | 10250572 | PDF, 482 KB |
| 20-NA-084 | Service bulletin | Mar 31, 2022 | 10209957 | PDF, 64 KB |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themChevrolet 7 model years
Buick 8 model years
A vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
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What owners reported
Source: NHTSA complaint databaseOwners of the 15 model years this bulletin names have filed 1,041 complaints with NHTSA since 2015. 239 of them name Engine — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.
Second complete powertrain failure on March 14, 2026 at 13,993 miles, nine days after first repair (complete transmission replacement for bone-dry sealed transmission). Symptoms: sudden loss of power on highway (unable to exceed 20 mph with accelerator fully depressed), hollow sound, noise described as "like a rock tumbling around…
2025 Buick Encore · Engine · filed with NHTSA Apr 1, 2026
The contact owns a 2023 Chevrolet Trailblazer. The contact stated that while driving 65 MPH, the “Engine Power Reduced" message was displayed, and the vehicle was unable to accelerate above 30 MPH. No warning lights were illuminated. The vehicle returned to normal functionality, but the failure became a regular occurrence.
2023 Chevrolet Trailblazer · Engine · filed with NHTSA Sep 19, 2024
My vehicle started overheating out of no where towed it to the shop, it’s been there for 2 weeks they’re actively waiting for a manufacturer engineer to tell them what to do because they can’t figure out how to fix it. On top of that there have been a lot of overheating issues cause by different parts on the vehicle.
2025 Chevrolet Trailblazer · Engine · filed with NHTSA Apr 16, 2026
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
More bulletins about the engine
Source: same model, same component group74 other manufacturer communications filed against these GM models under the same component group (engine), newest first. The eight newest are listed; the rest are on the Chevrolet list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| N242484750-02 | Warranty extension | Sep 1, 2026 | Special Coverage. Certain 2022 model year Buick Encore GX and Chevrolet Trailblazer vehicles, equipped with a 1.2L engine, may have a condi… |
| N242450640-02 | Warranty extension | Sep 1, 2026 | Special Coverage. Certain 2021 model year Buick Encore GX and Chevrolet Trailblazer vehicles, equipped with a 1.2L engine, may have a condi… |
| N232407740-03 | Warranty extension | Sep 1, 2026 | Special Coverage. Certain 2020 model year Buick Encore GX vehicles, equipped with a 1.2L engine, may have a condition that could cause the… |
| N252499670 | Service campaign | Oct 23, 2025 | Certain vehicles, equipped with a 1.4L engine, may have a condition that could cause the turbocharger to fail. If this condition occurs, th… |
| N242484750-01 | Warranty extension | Oct 20, 2025 | Special Coverage. Certain 2022 model year Buick Encore GX and Chevrolet Trailblazer vehicles, equipped with a 1.2L engine, may have a condi… |
| N242450640-01 | Warranty extension | Oct 20, 2025 | Special Coverage. Certain 2021 model year Buick Encore GX and Chevrolet Trailblazer vehicles, equipped with a 1.2L engine, may have a condi… |
| N232407740-02 | Warranty extension | Oct 20, 2025 | Special Coverage. Certain 2020 model year Buick Encore GX vehicles, equipped with a 1.2L engine, may have a condition that could cause the… |
| PIE0831A | Service bulletin | Jun 5, 2025 | This engineering information (EI) closure ends the need for gathering further information from technicians in regard to the Malfunction Indi… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet and Buick, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM 20-NA-084 a recall?
No. A service bulletin is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the 20-NA-084 repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way.
Which vehicles does 20-NA-084 cover?
The manufacturer filed it against 15 model years across 2 brands (Chevrolet and Buick): 2025 Buick Encore, 2024 Buick Encore, 2023 Buick Encore, 2022 Buick Encore, 2021 Buick Encore, 2020 Buick Encore and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.