BMW bulletin B170121
What it saysThe quick disconnect coupling on the cylinder head coolant vent line could break at the cylinder head. NHTSA’s full summary ↓
BMW filed this with NHTSA as a service bulletin dated Apr 1, 2022, received May 31, 2022, about the engine — 2 documents under this number. It names 48 model years (2016–2021). 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 communicationThe quick disconnect coupling on the cylinder head coolant vent line could break at the cylinder head. This would lead to loss of coolant from the engine.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| B170121 | Service bulletin | Apr 1, 2022 | 10212788 | not found |
| B170121 | Service bulletin | Feb 1, 2022 | 10214256 | not found |
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 themand 2 more on this site: 2018 BMW i8, 2017 BMW i8.
Also filed against model years this site has no page for: 2017 BMW 750LXI; 2018 BMW 8 Series; 2018 BMW B7 Alpina; 2017 BMW M760LI; 2018 BMW M760LI; 2018 BMW M850I.
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 42 model years this bulletin names have filed 1,555 complaints with NHTSA since 2015. 567 of them name Engine, Fuel/Propulsion 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.
On the 2016 BMW 3 Series, the 16 owners who gave an odometer reading for Engine reported it at a median of 100,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
I have a BMW 430i Gran Coupe, there was a system coolant leak and now they are saying the entire system needs to be replaced because the plastic cracked and eroded from wear and tear. I began checking and found that over 1 million BMW vehicles were recalled for coolant system problems. My car seems it wasn't covered under the recall.
2017 BMW 4 Series · Fuel/Propulsion System · filed with NHTSA Jan 13, 2023 · ODI 11501682
On , I was driving down the road and a indicator light went off, indicating a malfunction. When I pulled over to the side, I shut the car off. I noticed something around the drivers side front end of the car. When I exited the vehicle, I seen fire (flame) coming from the front drivers side. It was located right in front of the tire.
2017 BMW 2 Series · Engine · filed with NHTSA Aug 23, 2026 · ODI 11758915
The contact owns a 2018 BMW X4. The contact received notification of NHTSA Campaign Number: 24V608000 (Engine and Engine Cooling, Electrical System); however, the part to do the recall repair was not yet available. The dealer was contacted on several occasions; however, the contact was informed that parts were not available.
2018 BMW X4 · Engine · filed with NHTSA Jul 18, 2025 · ODI 11674611
In depth: 2020 BMW M 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 group92 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… |
| B064526 | Other | Sep 9, 2026 | Intake Muffler Return |
| 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 |
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 B170121 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 B170121 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 B170121 cover?
The manufacturer filed it against 48 model years: 2021 BMW 2 Series, 2020 BMW 2 Series, 2019 BMW 2 Series, 2018 BMW 2 Series, 2017 BMW 2 Series, 2016 BMW 2 Series and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.