Bonneville V6-3800 3.8L VIN L SFI (1995)
Oxygen Sensor: Description and Operation
PURPOSE
The exhaust Heated Oxygen Sensor (HO2S) is mounted in the exhaust system where it can monitor the oxygen content of the exhaust gas stream.
OPERATION
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 Tech 1 scan tool.
By monitoring the voltage output of the oxygen sensor, the Powertrain Control Module (PCM) calculates what fuel mixture command to give to
the injector (lean mixture-low HO2S voltage = rich command, rich mixture-high HO2S voltage = lean command).
The heated oxygen sensor circuit, if open, should set a Diagnostic Trouble Code (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.
