BMW 340I 2016–2018 — technical service bulletin
Bulletin B120318 · NHTSA communication 10153743 · issued Jan 1, 2019
Technical service bulletin
communication type
Engine and Engine Cooling
component
2016–2018
model years
5
vehicle entries
Official summary
No audible difference in exhaust with m performance power and sound kit.
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.