C 3500 Truck 2WD V8-454 7.4L VIN J SFI (1999)
The VCM calculates what fuel mixture command to give to the injectors based upon voltage output of the oxygen sensor, (lean mixture - low HO2S
voltage = rich command, rich mixture - high HO2S voltage = lean command). The heated oxygen sensor voltage can be monitored with a scan tool.
Depending upon the configuration of the vehicle's exhaust system, the number of oxygen sensors may vary. The pre-catalyst (HO2S Bank 1 Sensor 1 and
Bank 2 Sensor 1) oxygen sensors are positioned between the exhaust manifold and catalytic convener. The post-catalyst (HO2S Bank 1 Sensor 2, Bank 1
Sensor 3, and Bank 2 Sensor 2) oxygen sensors are positioned between the catalytic converter and the muffler.
When the VCM detects an HO2S signal circuit that is low, the VCM will set one of the following DTCs:
^
DTC P0131 Bank 1 Sensor 1 HO2S
^
DTC P0137 Bank 1 Sensor 2 HO2S
^
DTC P0143 Bank 1 Sensor 3 HO2S
^
DTC P0151 Bank 2 Sensor 1 HO2S
^
DTC P0157 Bank 2 Sensor 2 HO2S
When the VCM detects an HO2S signal circuit that is high, the VCM will set one of the following DTCs:
^
DTC P0132 Bank 1 Sensor 1 HO2S
^
DTC P0138 Bank 1 Sensor 2 HO2S
^
DTC P0144 Bank 1 Sensor 3 HO2S
^
DTC P0152 Bank 2 Sensor 1 HO2S
^
DTC P0158 Bank 2 Sensor 2 HO2S
The VCM has the ability to monitor HO2S switching, transition time, and incorrect voltage ratio problems. When the VCM detects sluggish HO2S
activity, the VCM will set one of the following DTCs:
^
DTC P0133 Bank 1 Sensor 1 HO2S
^
DTC P0153 Bank 1 Sensor 2 HO2S
When the VCM detects no HO2S activity, the VCM will set one of the following DTCs:
^
DTC P0134 Bank 1 Sensor 1 HO2S
^
DTC P0140 Bank 1 Sensor 2 HO2S
^
DTC P0146 Bank 1 Sensor 3 HO2S
^
DTC P0154 Bank 2 Sensor 1 HO2S
^
DTC P0160 Bank 2 Sensor 2 HO2S
A fault in the heated oxygen sensor heater element, ignition voltage, 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, one of the following DTCs will
set:
^
DTC P0135 Bank 1 Sensor 1 HO2S heater
^
DTC P0141 Bank 1 Sensor 2 HO2S heater
^
DTC P0147 Bank 1 Sensor 3 HO2S heater
^
DTC P0155 Bank 2 Sensor 1 HO2S heater
^
DTC P0161 Bank 2 Sensor 2 HO2S heater
