Acura bulletin D.1.6.4
Acura filed this with NHTSA as a over-the-air update dated May 18, 2026, received Jun 2, 2026, about the electrical system — 2 documents under this number: B21673, B21674. It names 6 model years (2019–2023). A over-the-air update is not a safety recall — there is no NHTSA campaign number and no federal requirement — but it is usually work the manufacturer pays for on the vehicles it names; the dealer checks the VIN against the manufacturer’s list.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationOver The Air Update - Vehicles equipped with the System Updates application are capable of downloading and installing Over the Air System Updates. System Updates contain upgrades that fix a variety of operational errors and/or enhancements that add new functionality. Information for the various software releases can be found in this document. Software version: D.1.6.4
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B21673 | Over-the-air update | May 18, 2026 | 11033180 | not yet checked |
| B21674 | Over-the-air update | May 18, 2026 | 11033179 | not yet checked |
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.
Common questions
Source: NHTSA, 49 CFR 579.5Is Acura D.1.6.4 a recall?
No. A over-the-air update 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 D.1.6.4 repair free?
A over-the-air update is usually paid by the manufacturer on the vehicles it names, within the terms and time limit the document sets; the dealer checks the VIN against the manufacturer’s list.
Which vehicles does D.1.6.4 cover?
The manufacturer filed it against 6 model years: 2021 Acura RDX, 2020 Acura RDX, 2019 Acura RDX, 2023 Acura TLX, 2022 Acura TLX, 2021 Acura TLX. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.