BMW bulletin B521125
What it saysIf the seat ventilation is deactivated via the switch or due to parking the vehicle, the fans in the seat cushionor under the seat cushion surface are unpleasantly loud. NHTSA’s full summary ↓
BMW filed this with NHTSA as a service bulletin dated Aug 21, 2025, received Aug 24, 2025, about the seats. It names 6 model years (2020–2025). 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 communicationIf the seat ventilation is deactivated via the switch or due to parking the vehicle, the fans in the seat cushionor under the seat cushion surface are unpleasantly loud. The fans speed up loudly twice and then turn off. The functionality of the fans is not impaired. This behavior only occurs after the vehicle had been programmed to I level S18A- 25-07-520 and higher; upto, but not including S18A- 25-07-551.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B521125 | Service bulletin | Aug 21, 2025 | 11022110 | PDF, 178 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 6 model years this bulletin names have filed 14 complaints with NHTSA since 2015. 7 of them name Electrical System — 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.
My vehicle mileage was about 50,000 miles and well maintained by BMW dealership in my area. I was driving to work when suddenly my vehicle alerted me to a fault on display panel showing a power supply fault. The message said i should stop driving and call roadside assistance. The vehicle was towed to BMW dealership.
2020 BMW 8 Series · Electrical System · filed with NHTSA Aug 21, 2024 · ODI 11609934
Customer filing a complaint against BMW for untimely resolution of Recall #25V644. This recall is a known Safety Risk which began in the summer of 2025. It is now December 4, 2025, and discussions today with BMW North America, they cannot provide me an ETA of when parts will be available for my vehicle.
2022 BMW 8 Series · Electrical System · filed with NHTSA Dec 4, 2025 · ODI 11702940
The contact owns a 2022 BMW 840I. The contact received notification of NHTSA Campaign Number: 25V644000 (Electrical System) in 2025. The contact had been working with the local dealer and was informed that parts were not available for the recall repair.
2022 BMW 8 Series · Electrical System · filed with NHTSA Apr 14, 2026 · ODI 11731178
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 seats
Source: same model, same component group2 other manufacturer communications filed against the BMW 8 Series under the same component group (seats), newest first.
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for BMW, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is BMW B521125 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 B521125 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 BMW warranty extension on file lists the ones BMW has filed.
Which vehicles does B521125 cover?
The manufacturer filed it against 6 model years: 2025 BMW 8 Series, 2024 BMW 8 Series, 2023 BMW 8 Series, 2022 BMW 8 Series, 2021 BMW 8 Series, 2020 BMW 8 Series. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.