Oxygen sensor functioning

Should sensor 2bank 1 work the same as bank 1 sensor 1?checked exhaust back pressure was 0 psi but i noticed catylist convert muffler was removed.watch the vedio here!

If there is no catalytic converter, then the upstream and downstream sensors (b1s1 and b1s2) will mirror each other.
This is also true if the catalytic converter is no longer functioning.

So if catalytic converter is removed,will the car set p0420 ?

cyrus.nk wrote: So if catalytic converter is removed,will the car set p0420 ?

Absolutely. Most catalyst monitors will pick up on that VERY quickly.

Ok thanks.so the best option is to replace with a new one?

That's about the only way to get rid of the p0420

Once you fix it you should see something like this at normal idle when the engine and cats and senors are hot and working.

Don't forget to check for stuff that killed the cat before replacement. Misfires, skewed fuel trims, burning oil/coolant, like that.

Thanks guys for your advices but unfortunately here can't get CAT.

Instead of starting a new thread I searched and thought it would be better if I posted my question to this thread. Apologies if it is considered a hijack. So, my question is, does the PCM use the downstream O2 sensor to adjust fuel trims at all? Going thru Paul's classes and spent some time searching around on the internet. Basically I'm getting mixed signals (get it..."mixed signals" ). I even read a couple threads that stated some cars do use the downstream sensor to adjust fuel trims and some don't. But I don't quite understand why the downstream would be used for fuel trims. It seems to me downstream is only used to measure cat efficency. Don't quite understand how it is possible if B1S1 is sending one signal and B1S2 would also be sending a signal for fuel trims abecause that would seem to me that they could conflict. Is there a yes or no answer to this question or is it "maybe"? Thanks.

Sorry sir, but I think the answer is indeed 'maybe'. Or, more like 'sort of'. :lol:

Short answer, some makes/models DO use the downstream O2 for some degree of fuel control. It's all about 'fine tuning' catalyst performance, as I understand it, and controlling how much oxygen the catalyst is storing at a given time. Any more, just knowing how the catalyst is performing isn't good enough. :blink: The OE now wants to make sure the catalyst is performing at it's best across a wide range of conditions.

In my experience, IF a vehicle uses downstream fuel trims, then there's usually some kind of data PID to go along with it. I've also noticed that the 'weight' of the downstream fuel trim is very light compared to the main short term/long term trims. Most models I've seen won't let the trims run away with a downstream O2 problem, but there are exceptions of course:

Thanks Tyler. Paul's video was exactly what I was looking for. Made notes in my book I'm up to Section 5 right now, but I'm still on the 2012 class videos. Perfect. Thank you!