Audi A4 Allroad 2017–2018 — technical service bulletin
Bulletin A391821 2051558- · NHTSA communication 10144640 · issued Jun 15, 2018
Technical service bulletin
communication type
Power Train
component
2017–2018
model years
7
vehicle entries
Official summary
This bulletin contains repair instructions for when the message "four-wheel drive malfunction" shows up sporadically in the instrument cluster with DTC C05ED00.
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.