Diagnostic Trouble Codes (DTCS)
WARNING: This page is about a different car, the 2010 Volvo V70, 2009 Volvo V70, and 2008 Volvo V70. However, it is still accessible from the selected car via links, so may be relevant.
A diagnostic trouble code is stored if the control module detects a fault. There are approximately 5 diagnostic trouble codes for the accessory USB unit (AUU). A fault detected in the most recent driving cycle is defined as permanent. Other faults are defined as intermittent.