L300 V6-3.0L VIN R (2001)
Oxygen Sensor: Description and Operation
Heated Oxygen Sensor 1 (HO2S-1)
This vehicle uses wide-band lambda sensors to monitor the oxygen content of the exhaust gas stream. These sensors compare the oxygen content of
exhaust gas to the oxygen content of fresh reference air. The oxygen sensor has a fixed voltage on its signal wire, but varies the pump current to the
oxygen sensor to indicate the vehicle's current air/fuel ration. The ECM interprets this current as a lambda value where a lambda of 1 means a
stoichometric ratio (14.7:1). A value higher than 1 indicates a lean condition, and a lambda less than 1 indicates a rich condition. During closed loop
operation, the ECM compensates for a rich or lean condition by decreasing or increasing the injector pulse width as necessary. These oxygen sensors do
not switch between rich and lean states to drive to a commanded air/fuel ratio. The use of the lambda gives a very precise air/fuel reading, and allows the
vehicle to quickly reach the commanded state without switching.
When the engine temperature is below 37°C (99°F), the vehicle operates in open loop. The ECM begins pulsing the oxygen sensor heater ground to
minimize the time it will take to reach closed loop fuel control. The oxygen sensor should begin functioning within 12 seconds after the heater reaches
the proper temperature for operation. The heater is activated at key On.
