Limitations

In certain situations, the BLIS indicator light(s) may illuminate even when there are no other vehicles in the area monitored by the system.
NOTE
If the BLIS indicator lights illuminate occasionally even when there are no other vehicles in the blind area, this does not indicate a fault in the system.
In the event of a fault, Blind spot syst. Service required will be displayed.
The following are several examples of situations in which the BLIS indicator light(s) may illuminate even when there are no other vehicles in the area monitored by the system.

Light reflected from a wet road surface

The vehicle's own shadow against a large, light, smooth surface such as barriers between lanes on a highway

Sunlight directly in the camera when the sun is low on the horizon
Test yourself
A quick Volvo XC60 quiz: every answer comes with an explanation and a link to the manual page.