Check The Signal Waveform Of HO2S

Ignition switch is turned "OFF" and connect HO2S connector.
Start the engine.
With engine at operating temperature, monitor signal waveform of HO2S above with GDS.
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.