Not-EWRX
03-18-2008, 12:12 PM
I replaced my rear O2 sensor last night thinking it was bad. Before I replaced it it would do much of the same thing at idle. The readings would be constant and then fall off allmost to zero. I am at loss as to why the readings would be like this. I am going to post up a log While at idle. The car is an 02 wrx catless stage 2 XPT.
volt heat
0.1 0.04
0.09 0.04
0.08 0.16
0.08 0.8
0.08 3.62
0.09 3.62
0.1 3.62
0.1 3.62
0.09 3.62
0.08 3.62
0.08 3.62
0.1 3.62
0.1 3.62
0.1 3.6
0.12 3.54
0.1 3.52
0.1 3.4
0.09 0.06
0.08 0.06
0.09 0.08
0.09 0.84
0.08 3.62
0.08 3.6
0.08 3.54
0.08 3.54
0.1 3.56
0.1 3.62
0.1 3.62
0.1 3.62
0.1 3.62
0.1 3.56
0.1 3.18
0.08 0.08
0.08 0.04
0.08 0.08
0.08 0.14
0.1 0.84
0.1 3.62
0.09 3.62
0.09 3.64
Not-EWRX
03-18-2008, 12:14 PM
Well that didn't work. How do you post up logs on this site. I copied the info from excel and then pasted it inside of the code tags? What did I do wrong?
Not-EWRX
03-18-2008, 02:57 PM
Yes success!
Volt=Rear O2 Sensor (V)
heat=Rear O2 Heater Voltage (V)
Can any body give me some insight as to why the heater voltage would drop off like that?
It does it twice in this log.
Not-EWRX
03-19-2008, 12:17 PM
No body else has had similar problems with there O2 sensor readings?
Gethin
03-19-2008, 01:30 PM
most people with stage 2 cars (ie catless turbobacks) loose the rear o2 sensor.
if you are running catless with an 02 you dont need the rear o2 sensor. It's for monitoring the rear cat performance. If you do want to keep it, get the mechanical fix or electrical fix. This stops the CEL from showing. Or even better disable the rear o2 codes through a open source reflash. The numbers are pretty meaningless unless you have a cat. If you do want to keep it (pointless) i'd guess the numbers would be more normal with the mechanical fix as the sensor would be seeing similar gasflow as if there was a cat there.
IMHO.
quazimoto
03-19-2008, 03:37 PM
Could be your IAC valve causing this or dirty MAF as well.The votlage really has nothing to do with the sensor itself as it's just doing what it's supposed too.
Wheeler Bement
03-19-2008, 06:34 PM
I think it is normal, but could be wrong. I noticed my electronic fix did the same thing...but I had bigger issues with the electronic fix, and would not advise it. just turn the P0420 code off and be done with it.
http://forums.nasioc.com/forums/showthread.php?t=1405039
http://forums.nasioc.com/forums/showthread.php?t=1397452