EVAP Service Port
WARNING: This page is about a different car, the 2006 Nissan Titan. However, it is still accessible from the selected car via links, so may be relevant.
Positive pressure is delivered to the EVAP system through the EVAP service port. If fuel vapor leakage in the EVAP system occurs, use a leak detector to locate the leak.
Courtesy of NISSAN MOTOR CO., U.S.A.