On Board Diagnosis Logic

WARNING: This page is about a different car, the 2005 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.

To judge the malfunction, the A/F signal computed by ECM from the A/F sensor 1 signal is monitored not to be shifted to LEAN side or RICH side.

Fig 1: DTC P1274, P1284 A/F Sensor 1 - On Board Diagnosis Logic

Courtesy of NISSAN MOTOR CO., U.S.A.