Circuit Diagram

Fig 1: HO2S Circuit Diagram

Courtesy of HYUNDAI MOTOR CO.

If the HO2S is defective, abnormally high emissions may occur.
If the HO2S check results are normal, but the sensor output voltage is out of specification, check for the following items (related to air fuel ratio control system):
- Defective injector
- Air leaks in the intake manifold
- Defective volume air flow sensor, intake air temperature sensor, barometric pressure sensor and engine coolant temperature sensor.

Fig 2: HO2S Specification Table

Courtesy of HYUNDAI MOTOR CO.