from what i read is 3 wire
2 are 12 volt + and - for the heater to the O2 sensor. The tird wire suppose to feed 450 mv to the computer so it will run normal.
Voltage less than 450 MV = engine lean so computer will dump more fuel.
Greater than 450 mv will tell computer to lean out the car.

I am going to get a voltage regulator ML 317 to drop voltage to 450mv and see if it will sail thru emission test.

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