Roadmaster Estate Wagon V8-350 5.7L VIN P SFI (1996)
Oxygen Sensor: Description and Operation
Front Heated Oxygen Sensors (HO2S)
The Heated Oxygen Sensors are mounted in the exhaust system where they can monitor the oxygen content of the exhaust gas stream. The oxygen
present in the exhaust gas reacts with the sensor to produce a voltage output. This voltage should constantly fluctuate from approximately 100 mV (high
oxygen content - lean mixture) to 900 mV (low oxygen content - rich mixture).
The heated oxygen sensor voltage can be monitored with a scan tool. By monitoring the voltage output of the oxygen - sensor, the PCM calculates what
fuel mixture command to give to the injectors (lean mixture - low HO2S voltage = rich command, rich mixture - high HO2S voltage = lean command).
When the PCM detects an HO2S signal circuit that is low, the PCM will set the following DTCs:
^
DTC P0131 Bank 1 left front HO2S.
^
DTC P0151 Bank 2 right front HO2S.
^
DTC P0137 Bank 1 left rear HO2S.
^
DTC P0157 Bank 2 right rear HO2S.
When the PCM detects an HO2S signal circuit that is high, the PCM will set the following DTCs:
^
DTC P0132 Bank 1 left front HO2S.
^
DTC P0152 Bank 2 right front HO2S.
^
DTC P0138 Bank 1 left rear HO2S.
^
DTC P0158 Bank 2 right rear HO2S.
When the PCM detects no HO2S activity, the PCM will set the following DTCs:
^
DTC P0134 Bank 1 left front HO2S.
^
DTC P0154 Bank 2 right front HO2S.
^
DTC P0140 Bank 1 left rear HO2S.
^
[?DTC P0160 Bank 2 right rear 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 at start-up. When the PCM detects a malfunction in the HO2S heater circuits, the following DTCs will
set:
^
DTC P0135 Bank 1 left front HO2S heater.
^
DTC P0155 Bank 2 right front HO2S heater.
^
DTC P0141 Bank 1 left rear HO2S heater.
