D3: Check For O2 Sensor Failure

Run the engine for a period to warm the sensor and then maintain a steady speed of approximately 2500 rpm.
Measure the voltage between EM022/001 and EM022/002.

Is the voltage between 600mV and 1.0 Volt?

Yes
GO to D4, D4: Check For O2 Sensor Failure

No
Renew O2 sensor; reconnect plug(s).
GO to D7, D7: Stop