GM bulletin 23-NA-170
What it saysThis bulletin advises the tech to inspect deeper into what may be the main cause of an engine failure. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated May 16, 2025, received Oct 17, 2023, about the engine — 4 documents under this number. It names 86 model years across Chevrolet, GMC and Cadillac (2019–2025). 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 · Cadillac.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis bulletin advises the tech to inspect deeper into what may be the main cause of an engine failure.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 23-NA-170 | Service bulletin | May 16, 2025 | 11024486 | PDF, 138 KB |
| 23-NA-170 | Service bulletin | Mar 11, 2024 | 10251909 | PDF, 46 KB |
| 23-NA-170 | Service bulletin | Jan 16, 2024 | 10249946 | PDF, 51 KB |
| 23-NA-170 | Service bulletin | Sep 22, 2023 | 10244180 | PDF, 72 KB |
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 48 model years
and 8 more on this site: 2023 Chevrolet Suburban, 2022 Chevrolet Suburban, 2021 Chevrolet Suburban, 2025 Chevrolet Tahoe, 2024 Chevrolet Tahoe, 2023 Chevrolet Tahoe, 2022 Chevrolet Tahoe, 2021 Chevrolet Tahoe.
GMC 29 model years
and 21 more on this site: 2022 GMC Sierra, 2021 GMC Sierra, 2020 GMC Sierra, 2019 GMC Sierra, 2025 GMC Sierra 2500HD, 2024 GMC Sierra 2500HD, 2023 GMC Sierra 2500HD, 2022 GMC Sierra 2500HD, 2021 GMC Sierra 2500HD, 2020 GMC Sierra 2500HD, 2025 GMC Sierra 3500HD, 2024 GMC Sierra 3500HD, 2023 GMC Sierra 3500HD, 2022 GMC Sierra 3500HD, 2021 GMC Sierra 3500HD, 2020 GMC Sierra 3500HD, 2025 GMC Yukon, 2024 GMC Yukon, 2023 GMC Yukon, 2022 GMC Yukon, 2021 GMC Yukon.
Cadillac 9 model years
and 1 more on this site: 2021 Cadillac Escalade.
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 86 model years this bulletin names have filed 13,069 complaints with NHTSA since 2015. 11,184 of them name Engine, Power Train, Electrical System — 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 2019 Chevrolet Silverado, the 142 owners who gave an odometer reading for Engine reported it at a median of 71,396 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
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
I bought this car from a dealer .that buys buy back cars from Gm .when i bought the car the dealer stated all service have been done . well i took to get oil changed and chevy told me they had no record of this service.the 2024 corvette gets a free oil and trans service from chevy.it has got to be done before 7500 miles .well the dealer…
2024 Chevrolet Corvette · Power Train · filed with NHTSA Jun 23, 2026
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
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 group304 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 |
|---|---|---|---|
| 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… |
| N262568830 | Service campaign | Aug 4, 2026 | Certain vehicles listed above may have a condition in which the oil filter was not adequately tightened. Dealers are to check and tighten th… |
| N262552620 | Service campaign | May 11, 2026 | Certain vehicles may have a condition that could cause the cylinder 2 glow plug to fail. If this failure occurs, the Malfunction Indicator… |
| N262552610 | Service campaign | May 7, 2026 | Certain vehicles may have a condition that could cause the crankcase pressure sensor to fail. If this failure occurs, the Malfunction Indic… |
| N262548050 | Service campaign | Apr 24, 2026 | Certain vehicles, may have a condition that could cause the Catalytic Converter to fail. If this failure occurs, the Malfunction Indicator L… |
| N252494003-02 | Service campaign | Jan 21, 2026 | Certain vehicles listed above, may have a condition where the connecting rod and/or crankshaft engine components in these vehicles may have… |
| 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… |
| N252508341 | Service campaign | Sep 16, 2025 | Certain vehicles listed above, may have a condition that could cause the engine coolant control valve to fail an onboard vehicle diagnostic… |
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 and Cadillac, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM 23-NA-170 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-170 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-170 cover?
The manufacturer filed it against 86 model years across 3 brands (Chevrolet, GMC and Cadillac): 2025 Cadillac CT5, 2024 Cadillac CT5, 2023 Cadillac CT5, 2022 Cadillac CT5, 2025 Cadillac Escalade, 2024 Cadillac Escalade and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.