Hello.
I have some live data readings for my O2 sensors.

O2S11 reads -0.086mA to about 0.023mA and sometimes 0.00mA.
O2B1S2 moves around from 0.154V to about 0.735V.

Not sure if these reading are correct for my 2004 V70 2.4 non turbo.
I just got a P420 code and was wondering if the older O2 sensor could be the issue and not the catalytic converter itself.
Any help would be great. Thank you.

 

the purpose of the rear o2 sensor is to measure the cat's efficiency - which it does by calculating a differential between the two sensors. So yes, it could be either the sensors or the cat. Do you have any issues with the car consuming oil or running rich which can mess with the cat? It doesn't take much to throw a code so you may want to also look for any vacuum line or intake airway leaks.

 

Thanks for the reply.
I do think I have an exhaust leak somewhere because I'm starting to smell what seems to be a possible leak.
Also I did hear a hissing sound coming from the intake manifold area, I'm thinking maybe the PCV is leaking/clogged.
Maybe one or hopefully not all could be the cause of the code.

 

the way to test for the PCV is to place a surgeon's glove or similar latex type on over the oil filler (cap removed of course :-) ) = if it inflates you have positive crankcase pressure (not good), if it pulses up and down or sucks in a bit, you have a working PCV system. Hissing near the intake - spray around with some carb cleaner to see if anything sucks in.

 

Thanks for the info.
Glove test worked great, the glove got sucked into the oil filler.
Tried the spray around the intake but nothing happened.
I'm thinking possible exhaust leak.

 

Whadja find?

 

Hello.
I used the graph on the scanner and looks like the rear O2 sensor is all over the place. If the vehicle is at idle the graph will be somewhat steady, but suddenly it just goes all over place and when I increase the RPM's it gets even worse. I was advised that the rear O2 sensor should be somewhat steady with it's signal, but it's definitely not steady at all.
No exhaust leak found, took it in for an oil change and tech found no leaks.
I figured change the rear O2 sensor and see where that takes me. The car has about 149500 miles on it so I guess it's about time to change the sensor anyway.
Thank you.