Fail-safe Chart
WARNING: This page is about a different car, the 2004 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.
The ECM enters fail-safe mode if any of the following malfunctions is detected due to the open or short circuit. When the ECM enters the fail-safe mode, the MIL illuminates.
Courtesy of NISSAN MOTOR CO., U.S.A.