F13: Check For Heated O2 Sensor Continuity

With EM012 and EM023 disconnected, measure the resistance between EM012/014 and EM023/003.

Is the resistance < 0.5 ohms?

Yes
GO to F14, F14: Heated O2 Sensor Screen Ground Continuity

No
Inspect harness/connectors EM012 and EM023 for corrosion, damaged/pushed back pins.
Repair as required and reconnect plug(s).
GO to F19, F19: End