GM bulletin 24-NA-021
What it saysThis service bulletin provides a procedure to test and replace, if needed, the pressure sensor and/or the oil pump if the codes noted set due to the debris left in the pump during production. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Mar 28, 2025, received Jun 24, 2024, about the engine — 4 documents under this number. It names 10 model years across Chevrolet and Buick (2023–2025). 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 a procedure to test and replace, if needed, the pressure sensor and/or the oil pump if the codes noted set due to the debris left in the pump during production.
Trouble codes it names: P0521 P06DD P06DE all 3 read from the document itself; NHTSA’s summary names none
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 24-NA-021 | Service bulletin | Mar 28, 2025 | 11017256 | PDF, 238 KB |
| 24-NA-021 | Service bulletin | Aug 26, 2024 | 11008079 | PDF, 239 KB |
| 24-NA-021 | Service bulletin | Jul 17, 2024 | 11005374 | PDF, 453 KB |
| 24-NA-021 | Service bulletin | Jun 5, 2024 | 11002025 | PDF, 142 KB |
What the document itself lists
Parts the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| 25204203 | N/A PAN, LWR OIL | 1 | eBay Motors → |
| 25206966 | N/A FILTER, OIL | 1 | eBay Motors → |
Labour operation and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 4086708 | Inspection and Testing of Oil Pressure Sensor | 0.8 hrs |
Read by machine from the document NHTSA serves (4 pages), read Sep 30, 2026. A part number is shown only where it matches GM’s own catalogue shape, an operation only with its code and time, and a description only where the reader got it whole; anything it could not settle is left out, and the PDF is the record. Times are the manufacturer’s warranty allowances, not a quote. Listings and prices on eBay Motors are the seller’s.
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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 5 model years
Buick 5 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 10 model years this bulletin names have filed 547 complaints with NHTSA since 2015. 338 of them name Electrical System, 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.
On the 2024 Chevrolet Trax, the 15 owners who gave an odometer reading for Electrical System reported it at a median of 16,400 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
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 2025 Buick Envista. The contact stated that while driving at an undisclosed speed, the radio screen went black. The manufacturer was contacted and referred the contact to the NHTSA Hotline for assistance. The dealer was contacted, and an appointment was scheduled. The failure mileage was approximately 10,000
2025 Buick Envista · Electrical System · filed with NHTSA Sep 23, 2026
The instrument panel intermittently blacks out while driving. I have taken it back to the dealer twice and they are unable to reproduce the issue. The first time, they said it was a software issue and ran an update, but that did not fix the problem. I found online that this is a known issue so I contacted Buick Customer Care.
2024 Buick Envista · Electrical System · filed with NHTSA Apr 11, 2025
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 24-NA-021 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 24-NA-021 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 24-NA-021 cover?
The manufacturer filed it against 10 model years across 2 brands (Chevrolet and Buick): 2025 Buick Encore, 2024 Buick Encore, 2023 Buick Encore, 2025 Buick Envista, 2024 Buick Envista, 2025 Chevrolet Trailblazer and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.