Air Fuel Ratio (A/F) Sensor
Air Fuel Ratio (A/F) Sensor On-Vehicle InspectionWARNING: To avoid danger of being burned, do not touch exhaust system when system is hot. Sensor inspection should be performed when system is cool.
Heater
1. Disconnect A/F sensor connector.
2. Using ohmmeter, measure resistance of Sensor heater between terminals "VB" and "GND" at sensor connector. If found faulty, replace A/F sensor.
NOTE: Temperature of sensor affects resistance value largely. Make sure that sensor heater is at correct temperature.
A/F sensor heater resistance
2 - 3 Ohms at 20 degrees C (68 degrees F)
3. Connect A/F sensor connector securely.
Circuit Insulation Check
1. Disconnect connector from A/F sensor.
2. Using ohmmeter, check circuit insulation of A/F sensor. If faulty is found, replace A/F sensor.
- Between each heater terminal (1) and other than heater terminals (2).
- Between each terminal ((1), (2), (3) and (4)) of A/F sensor and A/F sensor body (5).
3. Connect A/F sensor connector securely.
Adjusting Resistor
1. Disconnect A/F sensor connector.
2. Using ohmmeter, measure resistance of adjusting resistor between terminals "R+" and "R-" at A/F sensor connector.
If found faulty, replace A/F sensor.
Adjusting resistor resistance
100 - 58000 Ohms at 20 degrees C (68 degrees F)
3. Connect A/F sensor connector securely.