I've been searching around but I can't seem to find the answer to this question. What readings should I be getting from my O2 sensor? I can monitor it using my diag cable, but have no idea what a voltage reading would be at idle, cruising, flooring it, etc.

Can anyone shed some light on this for me?

With engine at normal operating temperature (coolant temperature 80 degrees Celsius or more),
when racing engine a normal oxygen sensor output voltage should be 0.6-1.0 V.

The Evoscan diagnostics software states the following for O2 sensor readings:

Values of approx 0 to 0.9 Volts are normal. 0 being lean, 0.9 being very rich. The sensor voltage will oscillate between these extremes when under closed loop control. Under high loads, the voltage should never drop below 0.7 Volts. If it does, this means that the fuel mixture is too lean when on boost. Quite possibly there is a fault with the air flow sensor.

The addition of cone style induction kits, whilst improving top end power and throttle response is known to upset air/fuel ratios. Alteration of the ecu calibration (AKA a remap) is the solution.

Pretty much the same as what i286 said :D

It isn't the voltage persae you are looking for, but the waveform. A bad O2 sensor can have the right voltages, but be sluggish as hell, and overshoot badly.

DO NOT use a digital multimeter, if you are in closed loop, it will not be fast enough to measure and it will drive you nuts trying to read it - analogue meter is OK, but best to look at it on a 'scope.

Or one of those cheap O2 meters from fleabay (or the $12 job from Jaycar - its a kit so if you are handy with a soldering iron...) They will show the movement quite well, and show open/closed loop conditions.

Not sure how descriptive this is, but here is a log file of the reading as the car accelerated from 10kph to 82kph.

http://img.photobucket.com/albums/v492/mitchello/Picture2.png

Does it take long to run one of these reports?

Mohit, when you hook your diag thingo up to my car this week, can you run one of these report things too on it for me? Might get to the bottom of my fuel economy problems. Only if it doesn't take too long, just wanna know if my O2 sensor is responsible for my 16.5L/100km atm.

Honestly - that looks like you are in closed loop, and its working fine. Assumes a 1.8Hz output (18 peaks in the time it took you to accelerate, assumes 10 seconds) You definitly were not WOT, as you would be open loop.

Does it take long to run one of these reports?

Mohit, when you hook your diag thingo up to my car this week, can you run one of these report things too on it for me? Might get to the bottom of my fuel economy problems. Only if it doesn't take too long, just wanna know if my O2 sensor is responsible for my 16.5L/100km atm.

The report is basically just a log of the variables. That excerpt was only a few seconds worth.

Heathyoung, that's good to hear ;)

Does it take long to run one of these reports?

Mohit, when you hook your diag thingo up to my car this week, can you run one of these report things too on it for me? Might get to the bottom of my fuel economy problems. Only if it doesn't take too long, just wanna know if my O2 sensor is responsible for my 16.5L/100km atm.
Yeh no probs mate. We can plug the whole setup into your car and go for a drive to get longer/more accurate readings.