BMW bulletin B121125
What it saysA 740i Sedan, 740i xDrive Sedan (B58N - ICEV), or a 750e xDrive Sedan (XB1N - PHEV) may have one orboth of the following faults stored in the DME: 034AA5 - Mixture control bank 1, lambda regulation, mixture too lean… NHTSA’s full summary ↓
BMW filed this with NHTSA as a service bulletin dated Nov 12, 2025, received Sep 3, 2025, about the engine — 2 documents under this number. It names 4 model years (2024–2025). 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 communicationA 740i Sedan, 740i xDrive Sedan (B58N - ICEV), or a 750e xDrive Sedan (XB1N - PHEV) may have one orboth of the following faults stored in the DME: 034AA5 - Mixture control bank 1, lambda regulation, mixture too lean 034AA8 - Mixture control bank 1, lambda adaptation, mixture too rich And additionally with the faults above, these affected vehicles may have one or more of the followingirregular combustion-related faults also stored: 033812 033813 033814 033815 033816 033817 033818 033819
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B121125 | Service bulletin | Nov 12, 2025 | 11025668 | PDF, 195 KB |
| B121125 | Service bulletin | Aug 26, 2025 | 11022357 | PDF, 174 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 4 model years this bulletin names have filed 30 complaints with NHTSA since 2015. 2 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.
Booked the appointment with BMW of Portland for November, 10,2025 For 9 o'clock AM. Arrived at dealership, checked in and left vehicle. I was called about 45 minutes later and informed that they would not be able to preform the recall repair on my car due to parts that were needed and associated with the recall , asked me to pay for it…
2024 BMW 5 Series · Electrical System · filed with NHTSA Nov 10, 2025 · ODI 11698655
The contact owns a 2024 BMW 750E. The contact stated while driving at an undisclosed speed, the high-voltage system warning light illuminated. The contact continued to drive the vehicle a short distance, and then the drive train warning light illuminated.
2024 BMW 7 Series · Electrical System · filed with NHTSA Nov 13, 2025 · ODI 11699171
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 group52 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 |
|---|---|---|---|
| 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. |
| B110326 | Service bulletin | Aug 12, 2026 | This Service Bulletin provides instructions to clean the intake valves using the BMW Carbon Blaster Tool P/N 81 29 2 208 034 and the S68T /… |
| 1613911200 | Warranty extension | Aug 3, 2026 | the NVLD modules limited warranty for defects in materials and/or workmanship has been extended to 15 years / 150,000 miles as determined fr… |
| B110426 | Service bulletin | Jul 17, 2026 | The manual starting of electronic engine oil level measurement from inside the vehicle, usually afterperforming an engine oil service task… |
| B063926 | Other | Jul 13, 2026 | Starter Generator Return |
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 B121125 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 B121125 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 B121125 cover?
The manufacturer filed it against 4 model years: 2025 BMW 5 Series, 2024 BMW 5 Series, 2025 BMW 7 Series, 2024 BMW 7 Series. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.