Express 1/2 Ton Van V8-305 5.0L VIN M SFI (1998)
1 Sensor 3 sensor produces an output signal which indicates the oxygen storage capacity of the catalyst; this in turn indicates the ability of the catalyst
to convert the exhaust gases efficiently. If the catalyst is operating efficiently, the Bank 1 Sensor 2 sensor will produce a far more active signal than
that produced by the Bank 1 Sensor 3 sensor.
The HO2S sensors which are used in order to monitor the catalyst function are the same as the HO2S sensors which are used in order to control the
fuel. Bank 1 Sensor 2 and Bank 1 Sensor 3 are used primarily for catalyst monitoring. These sensors also play a limited role in fuel control. If a sensor
output indicates a voltage either above or below the 450 millivolt bias voltage for an extended period of time, the VCM will make a slight adjustment
to the fuel trim in order to ensure that the fuel delivery is correct for catalyst monitoring.
