GM bulletin 23-NA-122
What it saysThis service bulletin provides a procedure to fix an oil leak from a porous area at the cylinder head and how to fix it so that the engine does not have to be replaced. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated May 9, 2025, received Jan 13, 2024, about the engine — 2 documents under this number. It names 11 model years across Chevrolet and Buick (2020–2024). 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 fix an oil leak from a porous area at the cylinder head and how to fix it so that the engine does not have to be replaced.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 23-NA-122 | Service bulletin | May 9, 2025 | 11023481 | PDF, 420 KB |
| 23-NA-122 | Service bulletin | Dec 18, 2023 | 10248716 | not found |
What the document itself lists
Parts the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| 11547739 | N/A BOLT, CYL HD | — | eBay Motors → |
| 12641115 | N/A CLAMP, PCV | 1 | eBay Motors → |
| 24585201 | N/A PIPE, TURBO | 2 | eBay Motors → |
| 11612078 | N/A GASKET | 4 | eBay Motors → |
| 25194208 | BALR | 1 | eBay Motors → |
| 13499082 | SYS FRT | 1 | eBay Motors → |
Labour operation and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 4089088 | Add Loctite© to Cylinder Head Bolt | 3.6 hrs |
Read by machine from the document NHTSA serves (5 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 6 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 11 model years this bulletin names have filed 883 complaints with NHTSA since 2015. 215 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.
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
The contact owns a 2024 Buick Envista. The contact stated that while at a stoplight, the vehicle shut off unintendedly. Additionally, while driving at an undisclosed speed and accelerating, the vehicle stalled. The contact stated that the instrument cluster screen was blank. There were no warning lights illuminated.
2024 Buick Envista · Engine · filed with NHTSA May 14, 2025
My 2024 trailblazer lt's engine light came on about a month ago. I took it to a local dealership and they said it was caused by CCND. Diagnosed code P0128 in pass/fail status. They test drove it to get light to come on and it was unable to duplicate it. They cleared the codes. A month later it came back on.
2024 Chevrolet Trailblazer · Engine · filed with NHTSA Jan 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 23-NA-122 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 23-NA-122 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 23-NA-122 cover?
The manufacturer filed it against 11 model years across 2 brands (Chevrolet and Buick): 2024 Buick Encore, 2023 Buick Encore, 2022 Buick Encore, 2021 Buick Encore, 2020 Buick Encore, 2024 Buick Envista and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.