5.5.1 Description
The system uses 4 heated exhaust gas oxygen sensors for the feedback control of the fuel system and the diagnosis of the catalysts. The engine is split into 2 banks of 3 cylinders, with 2 sensors per bank. 1 sensor in each bank is upstream of the catalyst and the other sensor is downstream of the catalyst.
The sensors are monitored for electrical continuity, correct operation of the heaters, time to switch from rich to lean (t rich to lean ) and from lean to rich (t lean to rich ), correct voltage level while in lean or rich operation and correct control frequency (t period ).