Monitoring O2 sensor/voltage

[Zack]

Bruce,

Actually, the way I understand it from what's been said, ~0.45 volts is
applied to the sensor through some large resistance (~1 megohm).  The
resistance of the sensor when cold is extremely high, it's basically an
open circuit, so the ECU sees steady ~0.45 volts as long as the sensor is
cold (or if there's an open circuit caused by a faulty connection or
sensor).  Once the sensor heats up, its resistance drops to a value much
lower than that 1 megohm, and it also starts generating a voltage
proportional to the O2 in the exhaust, so the voltage the ECU sees at that
point is basically just the voltage generated by the sensor itself.
	
Zack
----------
> From: bruce plecan <nacelp at bright.net>
> To: diy_efi at efi332.eng.ohio-state.edu
> Subject: Re:Monitoring O2 sensor/voltage
> Date: Monday, February 23, 1998 1:43 AM
> 
> I'd appreciate a little clarification, on this GM O2 sensor monitoring.
> If all they did was measure the output from the sensor, then I could
> understand that it was just reading the voltage.  But, by appling a
> voltage to it, and it having to develope enough current, and voltage
> to alter that signal doesn't that change what the ecm is monitoring
> from straight voltage, to wattage?..
> TIA  Bruce    Further documentation of why I own several cone
>                      shaped hats...