Chevrolet bulletin 23-NA-186
What it saysThis bulletin advises of a new vacuum pump and pulley and a new way to route and secure the vacuum hose. NHTSA’s full summary ↓
Chevrolet filed this with NHTSA as a service bulletin dated Feb 20, 2024, received Feb 29, 2024, about the engine. It names 22 model years (2016–2024). 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.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis bulletin advises of a new vacuum pump and pulley and a new way to route and secure the vacuum hose.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 23-NA-186 | Service bulletin | Feb 20, 2024 | 10250780 | PDF, 86 KB |
What the document itself lists
The manufacturer titles it “Information on Gas Vacuum Pump Replacement Part Update”.
Parts the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| 97656980 | N/A PUMP, VAC | — | eBay Motors → |
| 97542180 | — | 1 | |
| 97657703 | — | 1 | |
| 98250712 | — | — |
Read by machine from the document NHTSA serves (3 pages), read Sep 30, 2026. A part number is shown only where it matches Chevrolet’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 themAlso filed against model years this site has no page for: 2016 Chevrolet 4500; 2017 Chevrolet 4500; 2018 Chevrolet 4500; 2019 Chevrolet 4500; 2020 Chevrolet 4500; 2022 Chevrolet 4500; 2016 Chevrolet LOW Cab Forward 3500; 2017 Chevrolet LOW Cab Forward 3500; 2018 Chevrolet LOW Cab Forward 3500; 2019 Chevrolet LOW Cab Forward 3500; 2024 Chevrolet LOW Cab Forward 3500; 2016 Chevrolet LOW Cab Forward 4500; 2017 Chevrolet LOW Cab Forward 4500; 2024 Chevrolet LOW Cab Forward 4500; 2024 Chevrolet LOW Cab Forward 5500.
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 7 model years this bulletin names have filed 232 complaints with NHTSA since 2015. 35 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 2020 Chevrolet Silverado 3500. The contact stated that while driving on at 70-73 MPH, the vehicle unexpectedly downshifted to first gear. The contact slammed on the brake pedal and pulled over to the side of the road. The vehicle was turned off. The contact stated that the tachometer had increased to over 3,000 RPM.
2020 Chevrolet Silverado 3500HD · Engine · filed with NHTSA Feb 10, 2025 · ODI 11641761
The contact owns a 2019 Chevrolet Silverado. The contact stated that on several occasions at various speeds, the contact observed an exhaust odor coming into the cabin of the vehicle from the vents. The vehicle was taken to two dealers where the failure was not able to be replicated. The manufacturer was notified of the failure.
2019 Chevrolet Silverado 3500HD · Engine · filed with NHTSA May 29, 2026 · ODI 11740851
The contact owns a 2017 Chevrolet Silverado 3500. The contact stated that while driving at various speeds, the vehicle failed to upshift while depressing the accelerator pedal. The check engine warning light was illuminated. The vehicle was taken to a local independent mechanic and was diagnosed with a stuck torque converter.
2017 Chevrolet Silverado 3500HD · Engine · filed with NHTSA Nov 25, 2024 · ODI 11627254
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 group83 other manufacturer communications filed against these Chevrolet 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 |
|---|---|---|---|
| N262572131-01 | Service campaign | Oct 23, 2026 | Customer Satisfaction Program. Certain vehicles listed above may have a condition in which the oil galley in the cylinder head was not dril… |
| N262572131 | Service campaign | Aug 28, 2026 | Customer Satisfaction Program. Certain vehicles listed above may have a condition in which the oil galley in the cylinder head was not dril… |
| N262544790 | Service campaign | Mar 16, 2026 | Customer Satisfaction Program. Certain vehicles listed above, equipped with Air Compressor Accessory Drive (RPO KUT), may be missing the ai… |
| 25-NA-339 | Service bulletin | Nov 6, 2025 | Under Field Actions N252494000, N252494001, the service procedure includes performing a PICO test on vehicle engines within the identified s… |
| 22-NA-080 | Service bulletin | Sep 6, 2025 | This technical bulletin provides a procedure to replace the camshaft actuator magnet to correct customer concerns of engine related shudder. |
| 25-NA-150 | Service bulletin | Jun 5, 2025 | This bulletin provides a procedure to check and replace the oil cooler seals before just replacing the oil cooler, for an oil leak. |
| 00-06-01-026R | Service bulletin | Jun 5, 2025 | This service bulletin provides information on replacing the intake manifold when the engine is replaced after severe internal engine damage. |
| 23-NA-170 | Service bulletin | May 16, 2025 | This bulletin advises the tech to inspect deeper into what may be the main cause of an engine failure. |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Chevrolet 23-NA-186 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-186 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. Every GM warranty extension on file lists the ones GM has filed.
Which vehicles does 23-NA-186 cover?
The manufacturer filed it against 22 model years: 2022 Chevrolet Silverado 3500HD, 2021 Chevrolet Silverado 3500HD, 2020 Chevrolet Silverado 3500HD, 2019 Chevrolet Silverado 3500HD, 2018 Chevrolet Silverado 3500HD, 2017 Chevrolet Silverado 3500HD and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.