Sonata GLS V6-2.5L (2000)
Oxygen Sensor: Testing and Inspection
The heated oxygen sensor senses the oxygen concentration in exhaust gas, converts it into a voltage, which is sent to the ECM. The oxygen sensor
outputs about 0 V when the air fuel ratio is richer than the theoretical ratio, and outputs about 5 V when the ratio is leaner (higher oxygen concentration
in exhaust gas.). The ECM controls the fuel injection ratio based on this signal so that the air fuel ratio is maintained at the theoretical ratio. The oxygen
sensor has a heater element which ensures the sensor performance during all driving conditions.
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):
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Faulty injector
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Air leaks in the intake manifold.
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Faulty air flow sensor, intake air temperature sensor, engine coolant temperature sensor.
