Which of these sensors is downstream O2?

[Majindan]

https://imgur.com/a/UldVw

I'm trying to determine if my downstream O2 is malfunctioning as the cat was replaced 10k ago and there is a Bosche sensor in now that I think is already dying.

 

[SpidermanGeek]

downstream is post-cat.

get the denso sensor from Amazon.

 

[Majindan]

downstream is post-cat.

get the denso sensor from Amazon.

Thanks for the effort, but I was referring to the Torque screenshot to determine which of those sensors was the O2 in question.

 

[JayRolla]

https://imgur.com/a/UldVw

I'm trying to determine if my downstream O2 is malfunctioning as the cat was replaced 10k ago and there is a Bosche sensor in now that I think is already dying.

I don't know about the photo but do you have a cel? I would just do the 02 sensor bypass for the rear.

 

[ATX-Runner]

What CEL code are you getting?

 

[Majindan]

I don't know about the photo but do you have a cel? I would just do the 02 sensor bypass for the rear.

Infamous P0420. Could my 2nd cat be failing? Cali spec '02. New sensors, upstream Denso, down is Bosche, front cat, all about 10k miles old.

 

[SpidermanGeek]

Thanks for the effort, but I was referring to the Torque screenshot to determine which of those sensors was the O2 in question.

Sorry, imgur is actually blocked at work for me. Can't see the pic.

 

[JayRolla]

Infamous P0420. Could my 2nd cat be failing? Cali spec '02. New sensors, upstream Denso, down is Bosche, front cat, all about 10k miles old.

Did you buy toyota part# denso or bosch or the crappy amazon cheap part store ones. I had those fail on my previous cars quickly. You want to use the OEM toyota branded ones. IMO.

 

[Majindan]

Did you buy toyota part# denso or bosch or the crappy amazon cheap part store ones. I had those fail on my previous cars quickly. You want to use the OEM toyota branded ones. IMO.

I didn't buy any of it. The downstream is Bosche, which is why I suspect it's the O2. Denso makes the OEM sensors, which is what I would be replacing the Bosche with...IF I can determine if I'm looking at the correct graph in Torque lol.

 

[Majindan]

Does no one know which sensor graph in Torque is for the rear O2?

 

[JayRolla]

Does no one know which sensor graph in Torque is for the rear O2?

The one with the most movement up and down (0-5v) will be the front main o2 sensor. The rear should have little movement and stay around .5v. An exhaust leak can also cause the rear o2 sensor to throw a code.

Its usually best just to replace both sensors.

 

[Majindan]

The one with the most movement up and down (0-5v) will be the front main o2 sensor. The rear should have little movement and stay around .5v. An exhaust leak can also cause the rear o2 sensor to throw a code.

Its usually best just to replace both sensors.

I wonder if the second cat which is still original, is cashed. Still, how would the 2nd cat throw a code since its past the downstream sensor?