BMW 340I 2016–2018 — technical service bulletin
Bulletin B120318 · NHTSA communication 10142926 · issued Jan 1, 2018
Technical service bulletin
communication type
Engine and Engine Cooling
component
2016–2018
model years
7
vehicle entries
Official summary
No audible difference in exhaust with "m performance power and sound kit
Vehicles covered
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.