Auxiliary Air Control (AAC) Valve System Test
WARNING: This page is about a different car, the 1995 Nissan 200SX. However, it is still accessible from the selected car via links, so may be relevant.
Faults in auxiliary air control valve system may set DTC 25 (P0505). If necessary, check for stored codes. See RETRIEVING CODES in the TESTS W/CODES - 1.6L article.