BMW bulletin B540421
BMW filed this with NHTSA as a service bulletin dated Oct 18, 2023, received Dec 20, 2021, about the visibility — 3 documents under this number. It names 41 model years (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.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThe front sunroof glass seal has shrunk, creating a gap which can cause wind noise or excess water entry.
Documents filed under this number
| Document | Kind | Dated | NHTSA id |
|---|---|---|---|
| B540421 | Service bulletin | Oct 18, 2023 | 10244239 |
| B540421 | Service bulletin | Sep 1, 2022 | 10225114 |
| B540421 | Service bulletin | Nov 1, 2021 | 10205090 |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5; the full text comes from the manufacturer or a dealer. 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. Quote it at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themand 1 more model years on this site.
A 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 BMW B540421 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 B540421 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 B540421 cover?
The manufacturer filed it against 41 model years: 2024 BMW X3, 2023 BMW X3, 2022 BMW X3, 2021 BMW X3, 2020 BMW X3, 2019 BMW X3 and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.