Express 1/2 Ton Van V8-5.7L VIN R (1999)
Oxygen Sensor: Description and Operation
Heated Oxygen Sensor (HO2S 1)
The exhaust Heated Oxygen Sensor (HO2S 1) is mounted in the exhaust manifold where it can monitor the oxygen content of the exhaust gas stream.
The oxygen content in the exhaust reacts with the sensor to produce 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 heated oxygen sensor, the VCM calculates what fuel mixture command to give to the injector (lean mixture-low
HO2S 1 voltage=rich command, rich mixture- high HO2S 1 voltage=lean command).
The heated oxygen sensor circuit, if open, should set a DTC P0134 and the Scan tool will display a constant voltage between 350-550 mV. A constant
voltage below 250 mV in the sensor circuit should set DTC P0131, while a constant voltage above 750 mV in the circuit should set DTC P0132. DTC
P0131 and DTC P0132 could also be set as a result of fuel system problems.
