A15: Check For Short to B+

With EM010 & EM012 disconnected, measure the voltage between EM010/023 & EM012/022

Is the voltage 0 (zero) V?

Yes
Go to A16 A16: Check For Short to B+ At O2 Sensor Heater

No
Inspect connectors EM010, EM012, & EM021 for corrosion, damaged / pushed back pins or repair the harness; reconnect plug(s).
Go to A18 A18: End