BMW bulletin B120523
What it saysThe customer states there is a Drivetrain Malfunction message displayed in the instrument cluster. NHTSA’s full summary ↓
BMW filed this with NHTSA as a service bulletin dated Mar 6, 2026, received Oct 1, 2023, about the power train — 4 documents under this number. It names 10 model years (2021–2024). 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 communicationWhat it applies to, as the document itself states it — the build window in the manufacturer’s own words, read by machine from the PDF NHTSA serves. The build date is on the certification label in the driver’s door jamb; the dealer settles a borderline vehicle by its VIN.
The customer states there is a Drivetrain Malfunction message displayed in the instrument cluster. In addition, the following fault memory entries are saved in the CCU (Combined Charging Unit): 0317F2 - High-voltage system, insulation fault detected: when switch contactors are closed. 0317F1 - High-voltage system, insulation resistance below warning threshold: when switch contactors are closed. The fault memory entries (isolation faults) can occur both individually and in combination, and must be traced back to the eDrive motor based on the ISTA test procedure. If the ISTA test procedure lists the possible cause of fault as “a metal chip is found behind the brush module” (between the brush module and the end shield of the electrical machine), then a repair is required. Refer to service solution no. 20000794435083 in Aftersales Information Research (AIR). Follow information in the Procedure section below
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B120523 | Service bulletin | Mar 6, 2026 | 11030059 | PDF, 250 KB |
| B120523 | Service bulletin | Dec 10, 2024 | 11012080 | PDF, 327 KB |
| B120523 | Service bulletin | Feb 6, 2024 | 10250361 | PDF, 788 KB |
| B120523 | Service bulletin | Sep 13, 2023 | 10242885 | PDF, 230 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 themAlso filed against model years this site has no page for: 2021 BMW IX.
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 9 model years this bulletin names have filed 231 complaints with NHTSA since 2015. 102 of them name Electrical System, Power Train — 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.
I brought a brand new BMW IX fully electric vehicle in May, 2023. A couple of weeks ago in early September, the “Emergency Call System Malfunction” warning light came on, and I can also smell a chemical burn from the vehicle. I dropped it off to Eastbay BMW in Pleasanton, California. 4350 Rosewood Drive, Pleasanton, California 94588.
2023 BMW iX · Electrical System · filed with NHTSA Sep 28, 2023 · ODI 11547159
The only way I could explain it was as if my brakes were failing. After joining the bmw i4 group on Facebook and having my kids record while driving. I was able to capture the issue. The vehicle drive train will malfunction causing the vehicle to move while not in motion when at a stop light. The vehicle will accelerate on its on.
2023 BMW i4 · Electrical System · filed with NHTSA Apr 23, 2025 · ODI 11656435
This is the 4th time I am having issues with this car. Major safety issues. Yesterday during during on the 405 freeway. It suddenly started to rain, the wiper malfunction while in traffic and pouring rain. A week before this incident, the steering of the car kept moving suddenly out of my line. This time my son was in the car.
2024 BMW i7 · Electrical System · filed with NHTSA Sep 3, 2025 · ODI 11684707
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 power train
Source: same model, same component group4 other manufacturer communications filed against these BMW models under the same component group (power train), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| B330124 | Service bulletin | Jun 6, 2026 | The vehicle will no longer move when put into gear. There may also be loud noise coming from the HEAT*(electric drivetrain)/Rear axles. *Ger… |
| B370124 | Service bulletin | Jul 13, 2024 | While driving at low speeds (15-40 mph) on flat road surfaces, a knocking noise from the front axle may beheard during steering wheel moveme… |
| MCAS4023 | Service bulletin | Sep 29, 2023 | BMW AG has requested the inspection of all dealer stock of the following part number(s) listed below to ensure the spacer is conformed to d… |
| B120422 | Service bulletin | Jul 1, 2023 | BMW AG has issued a Delivery Stop (effective December 1, 2022) on certain Model Year 2023 BMW iX SAV vehicles that were produced between Oct… |
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 B120523 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 B120523 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 B120523 cover?
The manufacturer filed it against 10 model years: 2024 BMW i4, 2023 BMW i4, 2022 BMW i4, 2024 BMW i5, 2024 BMW i7, 2023 BMW i7 and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone. The document itself sets the build window: built before 24 Feb 2023 — the build date is on the certification label in the driver’s door jamb.