Acura bulletin B21100A
What it saysServiceNews Article - There are several possible causes for the SRS DTC U3000-49 (Internal Failure of the SRS Unit) to be stored. NHTSA’s full summary ↓
Acura filed this with NHTSA as a service bulletin dated Nov 11, 2021, received Oct 28, 2021, about the air bags — 2 documents under this number. It names 10 model years (2020–2021). 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.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationServiceNews Article - There are several possible causes for the SRS DTC U3000-49 (Internal Failure of the SRS Unit) to be stored. If you can duplicate the DTC, the troubleshooting will take you through the step-by-step process in isolating the faulty component. In most situations, the SRS Unit should be last on the list of components to replace. Here is a quick tip for troubleshooting a faulty seat weight sensor.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B21100A | Service bulletin | Nov 11, 2021 | 10203504 | PDF, 25 KB |
| B21100A | Service bulletin | Oct 22, 2021 | 10202602 | PDF, 25 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 themA 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 10 model years this bulletin names have filed 893 complaints with NHTSA since 2015. 21 of them name Air Bags — 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.
The contact owns a 2021 Acura TLX. The contact received notification of NHTSA Campaign Number: 24V064000 (AIR BAGS); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue.
2021 Acura TLX · Air Bags · filed with NHTSA Dec 6, 2024 · ODI 11629335
I am submitting this complaint regarding a 2021 Acura ILX (VIN: ) that has been unreleasable for an extended period due to manufacturer inability to supply a required safety component. The vehicle was involved in an accident on July 6, 2025 and delivered to Caliber Collision in Corpus Christi, Texas.
2021 Acura ILX · Air Bags · filed with NHTSA Dec 19, 2025 · ODI 11706024
I purchased a new 2020 Acura Rdx in january of 2020. Very soon my wife and I noticed that from time to time when she was seated in the front passenger seat, the "air bag off" light would remain illuminated.
2020 Acura RDX · Air Bags · filed with NHTSA Jun 25, 2020 · ODI 11330820
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 air bags
Source: same model, same component group1 other manufacturer communication filed against these Acura models under the same component group (air bags), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| B18-021 | Service bulletin | Feb 28, 2026 | Service bulletin - This bulletin is a notification of a class action settlement relating to airbag inflators. American Honda is offering a C… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Acura, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Acura B21100A 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 B21100A 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 Honda warranty extension on file lists the ones Honda has filed.
Which vehicles does B21100A cover?
The manufacturer filed it against 10 model years: 2021 Acura ILX, 2020 Acura ILX, 2020 Acura MDX, 2021 Acura NSX, 2020 Acura NSX, 2021 Acura RDX and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.