Vanden Plas L6-4.0L (1990)
Oxygen Sensor: Description and Operation
The oxygen sensor, located in the exhaust down pipe after the first catalyst, is a device that produces voltage by conducting oxygen ions at
temperatures above 300° (572°F). In order to reduce the amount of exhaust gas and resulting emission needed to bring the sensor up to working
temperature, an internal electric heater is used. The tip portion of the sensor ceramic element is in contact with the exhaust gas. The remaining
portion of the ceramic element is in contact with ambient air via capillary action through the heater electrical wires.
The sensor voltage output switches between approximately 800 millivolts and approximately 200 millivolts depending on the oxygen level
differential between ambient air and exhaust gas on either side of the ceramic element. When the air/fuel ratio is richer than 14.7:1 (Lambda =
1.0), the voltage output is high; when the air/fuel ratio is leaner than 14.7:1 (Lambda = 1.0), the output voltage is low. Only a very small change
in air/fuel ratio is required to switch the oxygen sensor.
Cross Section
Characteristic
Voltage Trace
