BMW bulletin B640324
What it saysThe coolant changeover valve may develop a coolant leak when the outside temperatures go below 19°F (-7°C). NHTSA’s full summary ↓
BMW filed this with NHTSA as a service bulletin dated May 23, 2024, received Feb 1, 2024, about the engine — 3 documents under this number. It names 2 model years (2023–2024). 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 coolant changeover valve may develop a coolant leak when the outside temperatures go below 19°F (-7°C). The vehicles operating systems would also need to be at that same low temperature (example: being parked outside, overnight in low temperatures).
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B640324 | Service bulletin | May 23, 2024 | 11000511 | PDF, 462 KB |
| B640324 | Service bulletin | Feb 5, 2024 | 10250368 | PDF, 475 KB |
| B640324 | Service bulletin | Jan 26, 2024 | 10249419 | PDF, 298 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.
Doing the repair yourself, or pricing it before the shop does? Search the part by fitment on eBay Motors — the listing and the price are the seller’s.
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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 2 model years this bulletin names have filed 72 complaints with NHTSA since 2015. 21 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.
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
I was driving on Single Pedal Drive on a freeway with the 2024 BMW IX, there was a slow down ahead of me. I removed my foot from the pedal and waited for car to slow down, but car didn't slow down enough. Then I slammed the brakes hard, but the brake didn't engage. In fact, brakes were pushed back against my foot.
2024 BMW iX · Electrical System · filed with NHTSA Apr 3, 2025 · ODI 11652449
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 group5 other manufacturer communications filed against the BMW iX under the same component group (engine), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| B640326 | Service bulletin | May 7, 2026 | After starting up the vehicle, a distinct, constant, “humming” noise can be heard from the right area of the instrument panel. |
| B170124 | Service bulletin | Feb 25, 2026 | There is coolant leaking from under the car Low heater output Possible Check Control message “Drive, you can continue driving” (ID49) Pos… |
| 0064340200 | Service campaign | Dec 9, 2024 | Quality checks have determined that the coolant changeover valve may develop a coolant leak under verylow outside temperatures… |
| 0064290200 | Service campaign | Jul 11, 2024 | Quality checks have determined that the coolant changeover valve may develop a coolant leak under very low outside temperatures… |
| B640724 | Service campaign | May 24, 2024 | Quality checks have determined that the coolant changeover valve may develop a coolant leak under ver ylow outside temperatures… |
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 B640324 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 B640324 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 B640324 cover?
The manufacturer filed it against 2 model years: 2024 BMW iX, 2023 BMW iX. 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: 2024 BMW: built on or after 10 Mar 2023; built 10 Mar 2023 – 12 Jan 2024 — the build date is on the certification label in the driver’s door jamb.