Can Anyone Help Me Diagnose O2 Sensor Readings
#1
Can Anyone Help Me Diagnose O2 Sensor Readings
I have been playing with the Android Torque App data logging. I am trying to see whether I need to replace my O2 sensor(s) and I thought this would be an interesting test. I know roughly how the sensors work, but I don't have a good feel for what the readings should look like. I could not find the right combination of search terms to let me find out either. So, here goes.
Here are my readings from a cold start (and I started logging before I started the car). Can anyone tell me what this means?
I have been told that there should be a roughly constant back-and-forth to the readings. Based on that, I am wondering if Sensor 1 is OK and Sensor 2 is bad because:
Sorry for the giant image.
Thanks,
Chris
Here are my readings from a cold start (and I started logging before I started the car). Can anyone tell me what this means?
I have been told that there should be a roughly constant back-and-forth to the readings. Based on that, I am wondering if Sensor 1 is OK and Sensor 2 is bad because:
- Sensor 1 is a fairly constant up and down of roughly equal magnitude.
- Sensor 2 is stuck and out of range (above 1 volt) at the beginning.
- Sensor 2 seems to hang on the higher end a few other times as well (columns J-M and T-W in the picture).
Sorry for the giant image.
Thanks,
Chris
#2
Suzuka Master
iTrader: (1)
I was thinking of replacing them anyway, but it would be nice to know that I was doing it because it was needed as opposed to some of the preventative maintenance that I do. Also, I think this stuff is interesting... and if someone could confirm what I am thinking or tell me I am completely off base I would appreciate it.
With that said, I had an O2 sensor code embed, as a result of a check engine light, for the front bank, IIRC, a few years ago. The computer does a pretty good job at letting you know if something is wrong. It just popped up one day driving in hellish summer FL heat stop and go traffic. The car had around 110k ish miles on the odometer. I just purchased two new Denso's from Amazon and replaced them both at the same time when the code appeared, have not had any problems since.
Last edited by zeta; 06-03-2015 at 01:36 PM.
#3
That's great info, Zeta, thanks! I should have included that. It is an '03 CL-S with just shy of 140k miles. I have not gotten a code or a CEL from it, I was just realizing it was getting pretty high in miles and pretty low MPG. (I'm getting 15mpg, but that is almost 100% high traffic city driving.)
Thanks also for the thoughts on the sensors. I wasn't sure how much latitude the sensors had before giving me the P0141, and whether a new, good sensor would perform measurably better than one that might be *just* good enough.
And then there's the fear of how much of a PITA it will be to get 12 year old 140k mile O2 sensors out of their homes...
Thanks also for the thoughts on the sensors. I wasn't sure how much latitude the sensors had before giving me the P0141, and whether a new, good sensor would perform measurably better than one that might be *just* good enough.
And then there's the fear of how much of a PITA it will be to get 12 year old 140k mile O2 sensors out of their homes...
Last edited by Gibbelstein; 06-03-2015 at 01:56 PM. Reason: typos
#4
Suzuka Master
iTrader: (1)
That's great info, Zeta, thanks! I should have included that. It is an '03 CL-S with just shy of 140k miles. I have not gotten a code or a CEL from it, I was just realizing it was getting pretty high in miles and pretty low MPG. (I'm getting 15mpg, but that is almost 100% high traffic city driving.)
It may be prudent, though, to just replace the O2's at your 140K mileage interval. As you mention, they are 12 years old. RockAuto has a good price for Denso 2344621($22.79) and 2344727($42.89). They have a coupon for 5% floating on the web for further savings.
Also, you may want to clean your EGR ports if they have never been touched. They tend to get pretty built-up with char after awhile. Do a search here on the forum, there are plenty of threads related to the subject, if interested.
Last edited by zeta; 06-03-2015 at 02:32 PM.
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zeta (06-03-2015)
#7
Drifting
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#8
Thanks, guys. I have actually had those denso sensors in my Rock Auto cart for a few days now. I think I'll go ahead and pull the trigger on them since they are so old. To be fair, I don't try to diagnose my spark plugs before changing them. I just change them on schedule (ok, more or less on schedule...)
Thanks again, Zeta for the tips on pulling the old sensors.
For the hell of it, I can also try logging again after I change them to see if it is visibly different.
I'm still curious about whether anyone can explain what to look for when diagnosing these things. The few articles I could find online mostly describe how they work, but not much about how to tell when they have had it.
Thanks again,
Chris
Thanks again, Zeta for the tips on pulling the old sensors.
For the hell of it, I can also try logging again after I change them to see if it is visibly different.
I'm still curious about whether anyone can explain what to look for when diagnosing these things. The few articles I could find online mostly describe how they work, but not much about how to tell when they have had it.
Thanks again,
Chris
Last edited by Gibbelstein; 06-03-2015 at 04:30 PM. Reason: addition
#9
Drifting
They are suppose to test between .1 to .9 volts and reads 2 to 3 times per second.
Sorry can't read the graft from phone.
Sorry can't read the graft from phone.
Last edited by 01acls; 06-03-2015 at 04:48 PM.
#10
Thanks for the verification, 01acls. Do you know if having a sensor go beyond that range is an indication that something is definitely wrong? Again, just trying to understand these things better.
#11
Drifting
What happens is they get slow/lazy or read wrong by sending the wrong volts.
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