Freightliner 122SD 2019–2020 — technical service bulletin
Bulletin SF591 · NHTSA communication 10165425 · issued Sep 27, 2019
Technical service bulletin
communication type
Engine and Engine Cooling
component
2019–2020
model years
10
vehicle entries
Official summary
Field Service Campaign for Wabco HP Air Dryer Turbo Cut-off Valve
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.