H10: O2 Sensor Short Circuit to Ground

With EM024 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 H12, H12: Signal Ground 1 Continuity

No
Renew the O2 sensor and reconnect all plugs.
GO to H11, H11: Stop