GM bulletin 21-NA-147
What it saysThis service bulletin provides a repair procedure to correct a customer concern of Coolant and/or Oil Leak, Malfunction Indicator Lamp (MIL) Illuminatedâ. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Dec 13, 2023, received Dec 19, 2023, about the engine. It names 96 model years across Chevrolet, GMC, Buick and Cadillac (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.
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 a repair procedure to correct a customer concern of Coolant and/or Oil Leak, Malfunction Indicator Lamp (MIL) Illuminatedâ.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 21-NA-147 | Service bulletin | Dec 13, 2023 | 10247524 | PDF, 74 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 34 model years
GMC 16 model years
and 8 more on this site: 2021 GMC Canyon, 2020 GMC Canyon, 2019 GMC Canyon, 2018 GMC Canyon, 2017 GMC Canyon, 2016 GMC Canyon, 2017 GMC Terrain, 2016 GMC Terrain.
Buick 16 model years
and 8 more on this site: 2016 Buick Enclave, 2019 Buick LaCrosse, 2018 Buick LaCrosse, 2017 Buick LaCrosse, 2016 Buick LaCrosse, 2020 Buick Regal, 2019 Buick Regal, 2018 Buick Regal.
Cadillac 30 model years
and 22 more on this site: 2019 Cadillac CT6, 2018 Cadillac CT6, 2017 Cadillac CT6, 2016 Cadillac CT6, 2019 Cadillac CTS, 2018 Cadillac CTS, 2017 Cadillac CTS, 2016 Cadillac CTS, 2016 Cadillac SRX, 2022 Cadillac XT5, 2021 Cadillac XT5, 2020 Cadillac XT5, 2019 Cadillac XT5, 2018 Cadillac XT5, 2017 Cadillac XT5, 2022 Cadillac XT6, 2021 Cadillac XT6, 2020 Cadillac XT6, 2019 Cadillac XTS, 2018 Cadillac XTS, 2017 Cadillac XTS, 2016 Cadillac XTS.
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 96 model years this bulletin names have filed 10,258 complaints with NHTSA since 2015. 1,942 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.
On the 2016 Chevrolet Equinox, the 78 owners who gave an odometer reading for Engine reported it at a median of 88,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
Transmission slipped almost from start. Took three appointments and two years - If my shop foreman knew the third time, why did he not call and tell me we now know your problem. I finally got fed up and brought it in one more time. Starter from day ONE maybe 50% of time made loud bang when Bendix retracted. Shop refused to take it off!!!
2018 GMC Canyon · Engine · filed with NHTSA Jan 1, 2022 · ODI 11445813
GM had a recall on the 3.6 lgz equipped in trucks in canada. Cold weather caused oil pump to over pressurizing of oil and damage to oil cooler and lines. Leaking oil in to engine compartment and on roadway. This has happened to me twice now once in march of 2018 and now again in november 2019. Doing research this is a common complaint.
2017 GMC Canyon · Engine · filed with NHTSA Nov 20, 2019 · ODI 11281338
I was driving on express way 96W Left lane busy 5 o'clock traffic Car just died it was stop n go I could have been killed if it wasn't for a man that stopped behind me he couldn't help another person stopped and push the car in N To a grass area where at least I wouldn't be smashed in Called 911 state police inform help van He didn't…
2020 Chevrolet Blazer · Engine · filed with NHTSA Oct 25, 2023 · ODI 11551752
In depth: 2020 Chevrolet Blazer engine problems → · 2016 Chevrolet Colorado engine problems → · 2017 Chevrolet Equinox engine problems → · 2016 Chevrolet Equinox engine 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 engine
Source: same model, same component group181 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 |
|---|---|---|---|
| N262566800 | Service campaign | Oct 20, 2026 | Certain vehicles listed above may have a condition in which the incorrect transmission parts were used. Dealers will replace the transmissio… |
| N262570770-03 | Service campaign | Oct 16, 2026 | Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are t… |
| N262570770-02 | Service campaign | Sep 25, 2026 | Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to… |
| N262570770-01 | Service campaign | Sep 18, 2026 | Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to… |
| N262570770 | Service campaign | Sep 15, 2026 | Certain vehicles may have a condition in which the thermal break tabs induce stress into the radiator causing a coolant leak. Dealers are to… |
| 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… |
| N262546590-01 | Service campaign | Jul 15, 2026 | Certain vehicles listed above, may have a condition where coolant leaks from the radiator hose quick connect at the radiator inlet. This sp… |
| 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… |
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-147 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-147 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-147 cover?
The manufacturer filed it against 96 model years across 4 brands (Chevrolet, GMC, Buick and Cadillac): 2024 Buick Enclave, 2023 Buick Enclave, 2022 Buick Enclave, 2021 Buick Enclave, 2020 Buick Enclave, 2019 Buick Enclave and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.