BMW bulletin B120523
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.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThe 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 moduleâ€Â� (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 | not yet checked |
| B120523 | Service bulletin | Dec 10, 2024 | 11012080 | not yet checked |
| B120523 | Service bulletin | Feb 6, 2024 | 10250361 | not yet checked |
| B120523 | Service bulletin | Sep 13, 2023 | 10242885 | 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: 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.
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.
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.