Oxygen (O2) Sensor
| Refer to COMPONENT INDEX . |
The four wire O2 sensors are attached to, and protrude into the vehicle exhaust system. The emissions system uses a total of four sensors. The two upstream sensors are referred to as 1/1 and 2/1, the and two downstream sensors are referred to as 1/2 and 2/2. The left and right upstream sensors (1/1 and 2/1) are located in the left and right exhaust down-pipes before the catalytic convertors. The left and right downstream sensors (2/1 and 2/2) are located in the left and right catalytic convertors. Normal range of the O2 sensor output is a 0 to 1.0 volt analog to digital signal when the sensor is in normal operating temperature range. The output voltage is generated by comparing the oxygen content in the atmosphere, collected in a reference chamber to the oxygen content in the exhaust stream collected in a comparison chamber. When the oxygen content is high (caused by a lean air/fuel mixture) the sensor produces a low voltage. When the oxygen content is low (caused by a rich air/fuel mixture) it produces a higher voltage.