Anybody ever change the O2 sensor just because its old? or do We wait till it fails?
Supposedly they respond more slowly as they age. Whether you'd ever notice this in the real world is debatable...but as Futureman says, it's small potatoes, especially in the context of a major service or similar activity.
For a newer car, look for the OBD code(s). For an 80's car, look for failed emissions tests. You shouldn't see a drop in performance since the O2 sensor is in open loop on acceleration. Over time, you would see an increased use of fuel. Also, if your frequency valve is not 'buzzing,' it could be the O2 sensor.
Can a malfunctioning O2 sensor effect the fuel/air mixture either in the fuel distributor or at the WUR thus causing a rich exhaust emission?
more info than you probably want: The O2 sensor is an "Air Battery" that responds to the DIFFERENCE between what's inside, and outside of the pipe. When the ex is rich, it puts out close to .9V, when it's lean, it goes to 0. Counterintuitive 'cause the very name "O2 Sensor" implies lean /more air / sensing more air etc. There's a lot to learn about these little devices. Then there's the new wideband designs etc etc etc.
I think the more correct term for the O2 sensor is temperature sensor, since the temp is the one being monitor depending weather it's lean or rich
My understanding of the function of the O2 sensor is that it measures the amount of unburned fuel left in the exhaust gas and, thus, the amount of O2 needed to completely burn the fuel. With that info it signals the system to add or subtract fuel from the mix. I didn't think it had any heat-related function as far as actual measurement...
