BMW bulletin B340925
BMW filed this with NHTSA as a service bulletin dated Dec 17, 2025, received Jan 5, 2026, about the service brakes. It names 12 model years (2024–2026). 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 communicationThere may be an internal leakage in the brake fluid expansion tank (aka brake fluid reservoir). In the rarecase of a leak, the filling level sensor might malfunction over a relatively long period of time.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B340925 | Service bulletin | Dec 17, 2025 | 11026950 | 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 themAlso filed against model years this site has no page for: 2024 BMW M3; 2025 BMW M3; 2026 BMW M3; 2024 BMW M4; 2025 BMW M4; 2026 BMW M4.
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 B340925 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 B340925 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 B340925 cover?
The manufacturer filed it against 12 model years: 2026 BMW 3 Series, 2025 BMW 3 Series, 2024 BMW 3 Series, 2026 BMW 4 Series, 2025 BMW 4 Series, 2024 BMW 4 Series and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.