Trooper LS V6-3.5L (1998)
Oxygen Sensor: Description and Operation
Fuel Control Heated Oxygen Sensors
The fuel control heated oxygen sensors (Bank 1 HO2S 1 and Bank 2 HO2S 1) are mounted in the exhaust stream where they can monitor the oxygen
content of the exhaust gas. 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 to 900 mV. The heated oxygen sensor voltage can be monitored with a scan tool. By monitoring the voltage
output of the oxygen sensor, the PCM calculates the pulse width command for the injectors to produce the proper combustion chamber mixture.
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Low HO2S voltage is a lean mixture which will result in a rich command to compensate.
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High HO2S voltage is a rich mixture which will result in a lean command to compensate.
An open Bank 1 HO2S 1 signal circuit will set a DTC P0134 and the scan tool will display a constant voltage between 400-500 mV. A constant
voltage below 300 mV in the sensor circuit (circuit grounded) will set DTC P0131. A constant voltage above 800 mV in the circuit will set DTC
P0132. Faults in the Bank 2 HO2S 1 signal circuit will cause DTC 0154 (open circuit), DTC P0151 (grounded circuit) or DTC P0152 (signal voltage
high) to set. A fault in the Bank 1 HO2S 1 heater circuit will cause DTC P0135 to set. A fault in the Bank 2 HO2S 1 heater circuit will cause DTC
P0155 to set. The PCM can also detect HO2S response problems. If the response time of an HO2S is determined to be too slow, the PCM will store a
DTC that indicates degraded HO2S performance.
