P0420 always downstream O2?

[Majindan]

Just want to make sure before I buy a new one. Truck was throwing lean code until I cleaned the MAF properly, as soon as catalytic test completed I got this on Torque https://imgur.com/8Hl6Dhj. Also, how long does it take for that Evap test to complete? Cleaned battery post about two weeks ago, new OEM gas cap AND new Wix fuel filter last Friday. So tired of working on my truck, ready to just enjoy it lol.

 

[HighMiles]

I will check my O2 sensor code next time I drive.

I seem to remember the fault code from Torque identified it as the O2 sensor directly...

 

[Majindan]

I will check my O2 sensor code next time I drive.

I seem to remember the fault code from Torque identified it as the O2 sensor directly...

No rattle or sulphur odor, and I just crawled under the truck with a flashlight and both o2 sensors are about 5 months old BUT the downstream one is Bosche and upstream is Denso. All signs are pointing to the Bosche dying.

 

[HighMiles]

This is what mine says, and it is the downstream sensor as it is physically broken. It has not changed the running of the engine so I have not replaced it.