Check The Signal Waveform Of HO2S

IG "OFF" and connect HO2S connector.
Start Engine
With engine at operating temperature, monitor signal waveform of HO2S with GDS.

Fig 1: Normal Waveforms Of Upstream HO2S (Upper) & Downstream HO2S (Lower) With Chassis Ground Used
Courtesy of HYUNDAI MOTOR AMERICA

Fig 2: Normal Waveforms Of Upstream HO2S (Upper) & Downstream HO2S (Lower) With Sensor Ground Used
Courtesy of HYUNDAI MOTOR AMERICA
Is the sensor switching properly?
YES
- Go to "Check fuel filter" as follows.
NO
- Substitute with a known - good HO2S and check for proper operation. If the problem is corrected, go to "VERIFICATION OF VEHICLE REPAIR " procedure.