GM bulletin 21-NA-238
What it saysThis technical bulletin provides a procedure to inspect the front pump of the transmission for a possible leak. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated May 8, 2025, received Feb 7, 2023, about the power train — 7 documents under this number. It names 24 model years across Chevrolet and GMC (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 · GMC.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis technical bulletin provides a procedure to inspect the front pump of the transmission for a possible leak.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 21-NA-238 | Service bulletin | May 8, 2025 | 11020259 | PDF, 134 KB |
| 21-NA-238 | Service bulletin | Jul 18, 2024 | 11005345 | PDF, 149 KB |
| 21-NA-238 | Service bulletin | May 31, 2024 | 11001784 | PDF, 146 KB |
| 21-NA-238 | Service bulletin | Feb 20, 2024 | 10250774 | PDF, 70 KB |
| 21-NA-238 | Service bulletin | Jan 22, 2024 | 10250250 | PDF, 70 KB |
| 21-NA-238 | Service bulletin | Jan 3, 2024 | 10249004 | PDF, 496 KB |
| 21-NA-238 | Service bulletin | Jan 19, 2023 | 10231399 | PDF, 494 KB |
What the document itself lists
Parts the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| 24293986 | X SEAL, T/C FLUID | 1 | eBay Motors → |
| 24277112 | Page 2 May, 2025 Bulletin No.: 21-NA-238 | 1 | eBay Motors → |
| 85630659 | FLUID CLR PIPE | 1 | eBay Motors → |
| 84013962 | N/A SEAL-EXH SYS | — | eBay Motors → |
| 15126137 | — | — | eBay Motors → |
| 20987829 | — | — | eBay Motors → |
| 15077362 | — | — | eBay Motors → |
| 11548472 | — | — | eBay Motors → |
| 84526283 | — | — | eBay Motors → |
| 24052451 | PRESS | 1 | eBay Motors → |
| 11604747 | N/A BOLT, TRNS | 15 | eBay Motors → |
| 11548787 | — | 2 | eBay Motors → |
| 11548414 | N/A NUT, TRNS MNT | 3 | eBay Motors → |
| 85573625 | N/A MOUNT, TRANS | 1 | eBay Motors → |
Read by machine from the document NHTSA serves (3 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 12 model years
GMC 12 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 24 model years this bulletin names have filed 1,227 complaints with NHTSA since 2015. 357 of them name Power Train, Equipment — 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.
Sudden jerk power train and deceleration while driving and towing 5th wheel, immediate loss of power and could have been catastrophic. GM has a known defect that requires immediate attention and investigation to affirm this is a broad national problem with the Allison 10 speed 10L1000 transmission, specifically the defective transmission…
2023 Chevrolet Silverado 2500HD · Power Train · filed with NHTSA Jul 8, 2025
The valve body assembly is not letting it to shift right when driving from 50mph to 60 mph it has a clunking noise I have it replaced and is still not working correctly GM knows there is a problem with the 10 speed transmissions I have a 2023 3500 diesel with the same problem as the recalls on the 2020 to 2022 years It is doing the same…
2023 Chevrolet Silverado 3500HD · Power Train · filed with NHTSA Jun 27, 2026
There is an issue that is causing the batteries to die. This in return causes the Vehicle to go into Limp home mode with no warning. The "issue" was supposed to be resolved by the Dealer in March 2022. The resolution was that one battery was bad. The vehicle is equipped with two batteries. Each of which is sufficient to run the vehicle.
2020 GMC Sierra 2500HD · Power Train · filed with NHTSA Jan 3, 2023
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 power train
Source: same model, same component group58 other manufacturer communications filed against these GM models under the same component group (power train), newest first. The eight newest are listed; the rest are on the Chevrolet list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| N262567720 | Service campaign | Sep 17, 2026 | Certain vehicles may have received transmission mounting bolts that do not meet expected hardness specifications. Loose or failed bolts may… |
| N262560680 | Service campaign | Jun 10, 2026 | Certain vehicles may have a condition in which the bolts for the transmission control valve body may be loose or missing. Dealers will retor… |
| N242454441 -03 | Service campaign | Oct 9, 2025 | Certain vehicles listed above, may have a condition where the transmission control valve has worn, resulting in a gradual loss of pressure w… |
| 24-NA-262 | Service bulletin | Jun 3, 2025 | This bulletin helps aid the tech in possible 10L100 transmission noise that may be normal or abnormal depending on the concern noted. |
| 22-NA-182 | Service bulletin | May 16, 2025 | This service bulletin advises the technician to check if the transmission cooler lines are twisted to correct customer concerns of Harsh Shi… |
| PIE0824A | Service bulletin | May 10, 2025 | This engineering information (EI) closure ends the need for gathering further information from field in regard to fluid leaking at the outpu… |
| 24-NA-075 | Service bulletin | May 8, 2025 | This bulletin provides a procedure to add a shim to the rear axle to change the pitch of said axle to correct the angle of the axle to pinio… |
| PIE0824 | Service bulletin | Mar 27, 2025 | This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer lis… |
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 GMC, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM 21-NA-238 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 21-NA-238 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 21-NA-238 cover?
The manufacturer filed it against 24 model years across 2 brands (Chevrolet and GMC): 2025 Chevrolet Silverado 2500HD, 2024 Chevrolet Silverado 2500HD, 2023 Chevrolet Silverado 2500HD, 2022 Chevrolet Silverado 2500HD, 2021 Chevrolet Silverado 2500HD, 2020 Chevrolet Silverado 2500HD and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.