I completely agree with you except for in this case I don't get 12 volts and according to the diagnostic trouble chart it says to check for four volts and if it's over 4 Volts for longer than 5 minutes the O2 sensor is bad and if it has no voltage to check the wire and if the wire is okay to replace the ECM. I don't know what kind of Genius would put a heater circuit going through an ECM but that's kind of ridiculous if you ask me

 

ECM has a selection of 12 volt outputs.... and it seems to me, that a heater circuit is a likely candidate for one of 'em.... why you would only feed it 4 volts is a mystery to me. The 5 minutes I can understand, as by then, the O2 should be hot enough to operate properly. The wiring diagrams I have, don't say anything about voltages though..... I don't have the manual for that year......