Oxygen Sensor: Testing and Inspection

CIRCUIT DIAGRAM




TROUBLESHOOTING HINTS
1. If the HO2S is defective, abnormally high emissions may occur.
2. If the HO2S check results were normal, but the sensor output voltage is out of specification, check for the following items (related to air fuel ratio control system).
- Faulty injector
- Air leaks in the intake manifold.
- Faulty air flow sensor, intake air temperature sensor, engine coolant temperature sensor.




Using GST

INSPECTION (USING VOLTMETER)

NOTE:
1. Before checking, warm up the engine until the engine coolant temperature reaches 80 to 95 °C (176 to 205 °F)




1. Apply battery voltage directly between terminal 3 and terminal 4.

NOTE: Take care when applying the voltage. Damage will result if the terminals are incorrect or are short circuited.

2. Connect a digital-type voltmeter between terminal 1 and terminal 2.




3. While repeatedly racing the engine, measure the oxygen sensor output voltage.
4. if there is a problem, there may be an oxygen sensor malfunction.

Tightening torque: Heated oxygen sensor 40-50 Nm (400-500 kg.cm, 29-36 lb.ft)










HARNESS INSPECTION PROCEDURES