Envoy 2WD V6-4.3L VIN W (1998)
100 mV (high oxygen content - lean mixture) to 900 mV (low oxygen content - rich mixture).
PURPOSE
The heated oxygen sensor voltage can be monitored with a scan tool. By monitoring the voltage output of the oxygen sensor, the VCM calculates what
fuel mixture command to give to the injectors (lean mixture - low HO2S voltage = rich command, rich mixture - high HO2S voltage = lean command).
DIAGNOSIS
When the VCM detects an HO2S signal circuit that is low, the VCM will set the following DTCs:
^
DTC P0131 Bank 1 Sensor 1 HO2S
^
DTC P0151 Bank 2 Sensor 1 HO2S
^
DTC P0143 Bank 1 Sensor 3 HO2S
When the VCM detects an HO2S signal circuit that is high, the VCM will set the following DTCs:
^
DTC P0132 Bank 1 Sensor 1 HO2S
^
DTC P0152 Bank 2 Sensor 1 HO2S
^
DTC P0144 Bank 1 Sensor 3 HO2S
When the VCM detects no HO2S activity, the VCM will set the following DTCs:
^
DTC P0134 Bank 1 Sensor 1 HO2S
^
DTC P0154 Bank 2 Sensor 1 HO2S
^
DTC P0146 Bank 1 Sensor 3 HO2S
A fault in the heated oxygen sensor heater element or its ignition feed or ground will result in an increase in time to Closed Loop fuel control. This may
cause increased emissions, especially during start-up. When the VCM detects a malfunction in the HO2S heater circuits, the following DTCs will set:
^
DTC P0135 Bank 1 Sensor 1 HO2S heater
^
DTC P0155 Bank 2 Sensor 1 HO2S heater
^
DTC P0147 Bank 1 Sensor 3 HO2S heater
The VCM also has the ability to detect HO2S response, switching, transition time, and incorrect ratio voltage problems. If an HO2S response switching,
transition time, or ratio problem is detected, the VCM will store a DTC which indicates degraded an HO2S performance.
