Oxygen Sensor: Testing and Inspection
Heated Oxygen Sensor (HO2S) On-Vehicle InspectionHO2S
1. Check that HO2S signal is outputted properly.
If faulty condition is found, check the following.
- Wire harness and connections
- Exhaust system leakage
If check result is good, replace faulty HO2S.
HO2S heater
1. Turn off ignition switch and disconnect HO2S connector.
2. Check that voltage of HO2S connector (vehicle side) between terminals "1" and "2" is battery voltage when ignition switch is in ON position.
If faulty condition is found, check power supply circuit, ground circuit and connections.
3. Using ohmmeter, measure resistance of HO2S connector (sensor side) of sensor heater between terminals "3" and "4" at sensor connector.
If faulty condition is found, replace faulty HO2S.
NOTE: Temperature of sensor affects resistance value largely. Make sure that sensor heater is at correct temperature.
HO2S heater resistance
5.0 - 6.4 ohms at 20 °C (68 °F)
