B9: Heated O2 Sensor Short Circuit to Ground

With EM021 disconnected measure the insulation resistance between sensor pin 001 and sensor body.
Repeat for pin 003 and sensor body.

Is the resistance > 10M ohms?

Yes
GO to B11, B11: Signal Ground 1 Continuity

No
Renew the O2 sensor and reconnect plug(s).
GO to B10, B10: Stop