O2 sensor checked, how do these voltages look?

[Novakaine]

So, I tested my o2 sensor...i think.

 

Here is what i did: This is a three wire sensor, two white and one black.

 

The two white wires i assume are for the heating element, and the one black wire is the O2 sensor...is that right?

 

So I splice my multimeter positive to the black wire, and chassi grounded the negative.

 

The voltage fluctuated between .15 volts to .8 volts and crossed .5 volts 4 or 5 times every 10 seconds.

 

Is it time to replace the O2 sensor.

 

Also, I am thinking the 02 sensor is bad because i get about 19 - 20 mpg, on average, but i do drive around 75 mph.

 

And also, since i don't have a tach, i don't know the rpm, but curing idle the engine sounds like it gets a little low, and is about to stall, but then it revs a little higher and all is good. That only happens maybe 3 or 4 times, every 10 minutes.

 

What do you guys think?

[friendly_jacek]

So, I tested my o2 sensor...i think.

 

Here is what i did: This is a three wire sensor, two white and one black.

 

The two white wires i assume are for the heating element, and the one black wire is the O2 sensor...is that right?

 

So I splice my multimeter positive to the black wire, and chassi grounded the negative.

 

The voltage fluctuated between .15 volts to .8 volts and crossed .5 volts 4 or 5 times every 10 seconds.

 

Is it time to replace the O2 sensor.

 

Also, I am thinking the 02 sensor is bad because i get about 19 - 20 mpg, on average, but i do drive around 75 mph.

 

And also, since i don't have a tach, i don't know the rpm, but curing idle the engine sounds like it gets a little low, and is about to stall, but then it revs a little higher and all is good. That only happens maybe 3 or 4 times, every 10 minutes.

 

What do you guys think?

The voltage looks good for the traditional (non-wideband) sensor in closed feedback. At least it sounds similar to what I have seen on my OBD-2 reader. This is a front sensor, right? It would be abnormal in after-cat sensor in a warmed-up car though.

[Novakaine]

The voltage looks good for the traditional (non-wideband) sensor in closed feedback. At least it sounds similar to what I have seen on my OBD-2 reader. This is a front sensor, right? It would be abnormal in after-cat sensor in a warmed-up car though.

yup, this is the front sensor. If it is a good sensor, then my mileage is pretty crappy. Why do you think? Anything else i can check/do for better mileage?

[frag]

According to Chilton's, if the sensor's voltage crosses .5 volt less than 5 times in 10 seconds, the sensor may be faulty. I think 4 or five time like you write is at the very least a little borderline. A few of us on this board (Commuter is part of those I think) have found out that a «lazy» O2S will degrade fuel mileage without tripping a CEL. If your front O2 sensor has never been replaced, maybe you could replace it and see what happens.

[Tiny Clark]

If it has never been replaced, then do it. O2 sensors don't last forever.http://www.oxygensensors.com/

 

You can buy the 7/8" socket for it at Autozone, Advance, etc...

[shimonmor]

I replaced my front O2 sensor at 100k miles and I never had a CEL for it and I noticed a marked improvement in engine idleing and fuel economy. If you have around 100k miles...replace it! Good preventative maintenance.

[Novakaine]

I replaced my front O2 sensor at 100k miles and I never had a CEL for it and I noticed a marked improvement in engine idleing and fuel economy. If you have around 100k miles...replace it! Good preventative maintenance.

Thanks guys, I think I will replace it soon. I will let you all know if there was any difference.