P0139 O2 Sensor Circuit Slow Response Bank 1 Sensor 2.
Can anyone help point me in the right direction of what I need? Do I need a new O2 sensor, or is there an issue somewhere else in the system?
how much power in the sensor putting out, did u hook up a diagnostic tool to it?
AZ scanned it quick.
I haven’t look at anything else. I have no idea where one would start.
well i know on those orange scanners it’ll give you a number figure to see how f’ed ur o2’s are…
for example, i have 2, one of mine is shot and he other one is 75%+ shot.
I’ll stop by again tomorrow and have it rescanned to double check everything, as I may have taken a number wrong, because I thought he said bank 2 was the problem one.
What car?
If its '96 its OBD2 so it could very well have two front O2 sensors. Bank 1 is the front and bank 2 is the rear IIRC.
Would bank 2 be post Cat then?
i have a 1996 2.2l impreza. there are two o2 sensors. 1 pre and 1 post cat. bank 1 sensor two, i believe, was the code i got when my post-cat o2 sensor died.
I thank you kind sir for the info.
I’m going to double check the sensors tolerences before I replace it outright. Not too concerned about rushing to get it fixed. Car is still running great, and fuel mileage is not being affected to a point where I should get my panties in a tizzy.
I’m going to wait for a nice sunny, warm day, lol.
I’m glad it’s post-cat too, as I had that pipe replaced last fall, so it shouldn’t be as difficult to remove the sensor as it would’ve been the front, which is original from '96.
So, new question…
The light turned off today, but then turned back on at a later time. Does anyone know if it is possible for a shot O2 sensor to read good for a period of time? Or is once it is done, it is done, and I definitely have a wiring problem?
Still seeing absolutely NO less gas mileage either. No ill effects at all.
i’m pretty sure they just fail and die.
if the light is turning on, then eventually off… then there’s another possibility.
This ALSO happened on my 96 impreza… the wires running to the rear O2 sensor run directly above the exhaust piping. The wires actually got a little loose and drooped down, eventually melting from the heat. This caused an occasional short, which led to a random O2 sensor CEL that would turn on and off.
hope that helps
Thanks, I’ll roll under and look tonight.
fyi. I just used a universal 3-wire O2 sensor on mine. It worked great and was a shitload cheaper. it’s been over a year and it’s still working just fine.
From what I’ve found from digging, is that it is a conditional code, and a dead sensor would read a seperate code, so I’m really hoping it’s an obvious wiring issue as I don’t want to go chasing demons all over the car.
I’ll report back my findings this evening.