Probable Cause

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

Malfunction is detected when an improper voltage signal is sent to ECM from EVAP-CSPS. Possible causes are:

EVAP-CSPS circuit open or shorted.
Defective EVAP-CSPS.
Defective EVAP Canister Vent Control Valve (EVAP-CVCV).
Defective water separator.
Defective EVAP canister.
Faulty hose between EVAP-CVCV and water separator.