O2 sensor question

[zenwalk]

I get extremely poor gas mileage out of my 4x4 Terc, like maybe 150 miles/250km per tank. It is an automatic though. I tried disconnecting the O2 sensor to see if that made any difference. There was none. Same gas mileage, same performance, same idle characteristics. Is it safe to say that my O2 sensor isn't working? I was looking at some of the O2 sensor posts in the last while and was wondering if I can check the voltage with my multimeter. If so, do I just take a voltage measurement while it idles?

[takza]

The O2 wire to the ECU goes up on the pass side fender. Find the wire...using a dull knife...remove some insulation from one side of it...clamp on a small insulated alligator clip....run this wire inside to a digital multimeter (+)....then the mm (-) is clamped to a good ground.

Set the meter up on the dash...watch it cycle while driving. DON'T ground or short anything.

Set the meter to read tenths to see the cycling without going bonkers.

[4wdchico]

Pages EC-32 to EC-35 in the Factory Service Manual (see the link above that says "Read Factory Service Manual")gives an overview of the Feedback Fuel System (FFS). Page EC-35 concludes the section with a test procedure for the 02 sensor that does not require any wire stripping. I'd suggest doing the 02 sensor test. If your FFS passes the 02 sensor check it shows that the system, taken as a whole, has a shot at controlling the fuel mix correctly. Unfortunately, the test does not really check 02 the sensor function very well. But, if your car passes the test, putting in a new sensor will probably not be a total waste.