BMW bulletin B120721
What it saysCheck Control message (CCM) indicates: (ID 213): Stop, exercising due care. NHTSA’s full summary ↓
BMW filed this with NHTSA as a service bulletin dated Mar 4, 2024, received Dec 6, 2023, about the engine — 2 documents under this number. It names 47 model years (2017–2024). 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.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationCheck Control message (CCM) indicates: (ID 213): Stop, exercising due care. Voltage supply The Service Engine Soon light is on with the following DME Fault Code: 21B209 - Starter alternator / belt for 48V system (OSA_RIEMEN_RISS): Belt betweenCombustion engine and starter generator torn And/or one or more of the following other issues are also occurring: Noise in the area of the belt drive. Odor from the engine compartment. Smoke formation in the area of the belt drive. Drive belt damaged or prematurely worn. Torn drive belt.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B120721 | Service bulletin | Mar 4, 2024 | 10252038 | PDF, 405 KB |
| B120721 | Service bulletin | Nov 9, 2023 | 10245367 | PDF, 888 KB |
What the document itself lists
Labour operation and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 00 58 500 | Diagnosis Worktime Flat Rate (See below) | 2 FRU |
Read by machine from the document NHTSA serves (6 pages), read Sep 30, 2026. A part number is shown only where it matches BMW’s own catalogue shape, an operation only with its code and time, and a description only where the reader got it whole; anything it could not settle is left out, and the PDF is the record. Times are the manufacturer’s warranty allowances, not a quote. Listings and prices on eBay Motors are the seller’s.
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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: 2020 BMW 330E; 2019 BMW 540D; 2020 BMW 540D; 2022 BMW 540D; 2023 BMW 540D; 2020 BMW 550E; 2021 BMW 550E; 2020 BMW 640I.
A 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 39 model years this bulletin names have filed 1,514 complaints with NHTSA since 2015. 338 of them name Engine — 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.
On the 2019 BMW X5, the 18 owners who gave an odometer reading for Engine reported it at a median of 67,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
I own a 2023 BMW 530i affected by NHTSA recall campaign 26V-438 (BMW "Engine Starter" recall), issued July 8, 2026. Per BMW's own recall documentation, unexpected wear on an internal starter component can cause the starter to malfunction and, in an extreme case, cause a thermal event or fire when starting the engine OR while the engine…
2023 BMW 5 Series · Engine · filed with NHTSA Jul 25, 2026 · ODI 11752807
I am started to lease this car in August 2024. After 2 weeks, the car just halted, unable to move. Luckily this happened in my driveway. It took BMW more than 1 month to repair this. They had to change the combined charging unit with a different part number (upgraded part). At that time the car had roughly 200 miles on the odometer.
2024 BMW X5 · Engine · filed with NHTSA Apr 23, 2024 · ODI 11584824
On most modern BMW models (with Hot V V8 engines like the N/S 63) the coolant tank that is supposed to last at least the lifetime of the vehicle, only lasts about 40,000 Miles before cracking. The main issue is that the tank sits over the engine, which when coolant leaks, it will leak into the injectors causing engine misfires.
2022 BMW 5 Series · Engine · filed with NHTSA Sep 10, 2026 · ODI 11763306
In depth: 2019 BMW X5 engine problems →
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 engine
Source: same model, same component group70 other manufacturer communications filed against these BMW models under the same component group (engine), newest first. The eight newest are listed; the rest are on the BMW list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| 0011320800 | Service campaign | Oct 21, 2026 | The cylinder head cover was not installed correctly at the assembly plant. |
| 0012870600 | Service campaign | Oct 10, 2026 | Due to an implementation error in various OBD diagnostics in the vehicle's control units, in very rare cases itmay happen that stored fault… |
| 1171901000 | Warranty extension | Sep 22, 2026 | The Exhaust Gas Recirculation (EGR) Cooler (with EGR Valve) and the Auxiliary Exhaust Gas Recirculation (EGR) Cooler limited warranty for de… |
| B121126 | Service bulletin | Sep 9, 2026 | Potential customer complaints with no fault codes stored / No MIL displayed. 1. “Rough idle after idling for a longer period of time” 2. “Ve… |
| 0011460700 | Emissions | Aug 26, 2026 | The return springs on the exhaust camshaft followers (switchable rocker arm) may break. |
| B064426 | Other | Aug 22, 2026 | Air Flap Return |
| B130126 | Service campaign | Aug 14, 2026 | Delivery Stop - Exhaust System Gasket |
| 0018030200 | Service campaign | Aug 14, 2026 | An exhaust gas sealing ring between thelower catalytic converter and upper catalyticconverter may be missing (1). |
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 B120721 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 B120721 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 B120721 cover?
The manufacturer filed it against 47 model years: 2024 BMW 3 Series, 2023 BMW 3 Series, 2022 BMW 3 Series, 2021 BMW 3 Series, 2020 BMW 3 Series, 2019 BMW 3 Series and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.