GM bulletin 21-NA-169
What it saysThis service bulletin provides diagnostic information/procedures to aid the service technician in diagnosing 9T45/50/60 automatic transmissions with low mileage and DTCs current or history related to the control… NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Oct 23, 2024, received Apr 15, 2022, about the power train — 5 documents under this number. It names 57 model years across Chevrolet, GMC, Buick and Cadillac (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 · Buick · Cadillac.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis service bulletin provides diagnostic information/procedures to aid the service technician in diagnosing 9T45/50/60 automatic transmissions with low mileage and DTCs current or history related to the control solenoids and valves.
Trouble codes it names: P0746 P0747 P0796 P0797 P187D P187E P18A8 P2723 P2724 P27F0 P2818 all 11 read from the document itself; NHTSA’s summary names none
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 21-NA-169 | Service bulletin | Oct 23, 2024 | 11011012 | PDF, 184 KB |
| 21-NA-169 | Service bulletin | May 3, 2024 | 11000363 | PDF, 205 KB |
| 21-NA-169 | Service bulletin | Aug 2, 2023 | 10241856 | PDF, 85 KB |
| 21-NA-169 | Service bulletin | Aug 4, 2022 | 10217854 | PDF, 106 KB |
| 21-NA-169 | Service bulletin | Apr 7, 2022 | 10210286 | PDF, 85 KB |
What the document itself lists
Labour operation and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 8486018 | Perform Fluid Level Check and Evaluate Condition, Oil Pressure Checks and Service… | 1.5 hrs |
Read by machine from the document NHTSA serves (8 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.
Doing the repair yourself, or pricing it before the shop does? Search the part by fitment on eBay Motors — the listing and the price are the seller’s.
Find the automatic transmission for the 2025 Blazer →Affiliate disclosure: some links on this page are affiliate links. If you request a quote or buy through them we may earn a commission at no extra cost to you. Nothing on this page changes because of it.
Model years it names
Source: as the manufacturer filed themChevrolet 16 model years
GMC 10 model years
Buick 13 model years
Cadillac 18 model years
and 10 more on this site: 2023 Cadillac XT5, 2022 Cadillac XT5, 2021 Cadillac XT5, 2020 Cadillac XT5, 2025 Cadillac XT6, 2024 Cadillac XT6, 2023 Cadillac XT6, 2022 Cadillac XT6, 2021 Cadillac XT6, 2020 Cadillac XT6.
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 57 model years this bulletin names have filed 3,399 complaints with NHTSA since 2015. 1,427 of them name Electrical System, Power Train — 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 2020 Chevrolet Blazer, the 16 owners who gave an odometer reading for Power Train reported it at a median of 50,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
On February 4, 2026, my wife drove to the bank, a trip of about 10 to 15 minutes, and turned off the car at the ATM. When she tried to leave, the vehicle wouldn't start. After a while, she opened and closed the door and locked and unlocked the car twice with the remote control, and the vehicle started and she was able to drive, but all…
2024 Chevrolet Blazer · Electrical System · filed with NHTSA Feb 5, 2026 · ODI 11715867
On September 15,2026, my vehicle experienced a catastrophic los of power steering assist accompanied by severe heavy steering. Please review General Motors TSB 20-NA-215 & TSB 17-NA-158 both addressing this issue. My 2021 vehicle has a build date of September 19, 2020 which falls "directly" in the time frame covered by these bulletins.
2021 Cadillac XT6 · Electrical System · filed with NHTSA Oct 11, 2026 · ODI 11770401
MY 2023 CHEVY MALIBU HAS A MISSING TURBOCHARGER SCREW THAT RANDOMLY CAME OFF FROM UNDER A METAL PLATE ON ITS OWN, GMC HAS A RECALL ON 2022 -2023 CHEY MALIBU WITH TURBO CHARGER ISSUES BUT THEY WONT COVER MINES BECAUSE IT DIDNT COME FROM A CERTIAN FACTORY ALTHOUGH THEY KNOW A HELL OF ALOT OF CHEVY MALIBU OWNERS HAVE TURBO CHARGER ISSUES…
2023 Chevrolet Malibu · Electrical System · filed with NHTSA Feb 11, 2026 · ODI 11717268
In depth: 2020 Chevrolet Blazer electrical problems → · 2020 Chevrolet Blazer transmission and drivetrain problems → · 2020 Chevrolet Malibu electrical problems → · 2020 Chevrolet Malibu transmission and drivetrain problems →
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 group102 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 |
|---|---|---|---|
| N252502891-01 | Service campaign | Aug 20, 2026 | Certain vehicles may have a condition in which the internal differential nut was cross threaded or missing during assembly. Dealers will rev… |
| N252502890-01 | Service campaign | Aug 20, 2026 | Certain vehicles may have a condition in which the internal differential nut was cross threaded or missing during assembly. Dealers will rev… |
| N242471460-01 | Service campaign | Aug 20, 2026 | Certain vehicles may have been built with an Electric Drive Unit mounting bolt that is too long, causing damage to the Drive Unit case. Deal… |
| PIE0814B | Service bulletin | May 7, 2025 | This engineering information (EI) closure ends the need for requesting further information from technicians in regard to the Service AWD Lam… |
| PIP6036A | Service bulletin | Apr 2, 2025 | This Preliminary information communicates diagnostic aids for a surge or fishbite concern |
| 25-NA-001 | Service bulletin | Mar 13, 2025 | This service bulletin provides repair information to correct a customer concern of a transmission fluid leak. |
| PIE0814A | Service bulletin | Mar 12, 2025 | This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer lis… |
| 24-NA-232 | Service bulletin | Mar 7, 2025 | This technical bulletin provides repair information to correct a customer concern of Metallic Noise from Rear Differential on Acceleration. |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet, GMC, Buick and Cadillac, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM 21-NA-169 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-169 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 21-NA-169 cover?
The manufacturer filed it against 57 model years across 4 brands (Chevrolet, GMC, Buick and Cadillac): 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.