C9: O2 Sensor Short Circuit to Ground

With EM022 disconnected measure the insulation resistance between sensor pin 001 and sensor body.
Repeat for pin 002 and sensor body.

Is the resistance > 10 Mohms?

Yes
GO to C11, C11: Signal Ground 1 Continuity

No
Renew the O2 sensor and reconnect all plugs.
GO to C10, C10: Stop