GM bulletin 21-NA-118
What it saysThis technical bulletin provides a procedure to align the exhaust causing a vibration. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Jun 8, 2023, received Jun 20, 2023, about the engine. It names 16 model years across Chevrolet, GMC and Cadillac (2020–2023). 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.
Get the next GM bulletin for your model by email Weekly, only when something new is filed. Nothing else; one-click unsubscribe.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis technical bulletin provides a procedure to align the exhaust causing a vibration.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 21-NA-118 | Service bulletin | Jun 8, 2023 | 10237937 | PDF, 69 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.
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 exhaust system for the 2023 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 4 model years
GMC 4 model years
Cadillac 8 model years
A vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
Email me new GM bulletins for one of these models
A weekly email, sent only in a week when GM files something new with NHTSA for the model you pick — service bulletins, campaigns, warranty extensions, over-the-air notices, every model year. Nothing else is sent; one-click unsubscribe in every message. Separate from recall alerts.
What owners reported
Source: NHTSA complaint databaseOwners of the 16 model years this bulletin names have filed 987 complaints with NHTSA since 2015. 272 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.
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
I noticed a water sloshing sound behind the dash when first starting out for about a month. I didn’t get any warning lights or notice anything leaking under the car but when I checked under the hood the coolant reservoir was empty. I made appointment at GM dealership and they found I had a leak along the side seam of my radiator.
2021 Cadillac XT6 · Engine · filed with NHTSA Oct 20, 2026 · ODI 11772504
The contact owns a 2020 Cadillac XT6. The contact stated while driving at 35 MPH, the vehicle lost power. The vehicle was restarted from the Cadillac App via phone. The contact stated that during the second failure " The steering assist is reduced drive with care" warning message and the check engine warning light illuminated.
2020 Cadillac XT6 · Engine · filed with NHTSA Dec 23, 2024 · ODI 11632207
In depth: 2020 Chevrolet Blazer 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 group99 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 |
|---|---|---|---|
| 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… |
| N252540910 | Service campaign | Feb 25, 2026 | Service Update. Certain vehicles listed above may have a condition in which a quality issue with the engine was identified. Dealers will re… |
| N252508350 | Service campaign | Oct 21, 2025 | Certain vehicles listed above, may have a condition that could cause the engine coolant thermostat to open at a lower temperature than inten… |
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 21-NA-118 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-118 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-118 cover?
The manufacturer filed it against 16 model years across 3 brands (Chevrolet, GMC and Cadillac): 2023 Cadillac XT5, 2022 Cadillac XT5, 2021 Cadillac XT5, 2020 Cadillac XT5, 2023 Cadillac XT6, 2022 Cadillac XT6 and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.