Where's the OBD reader gurus...

[joel2000]

So, here's the deal...

2016 Ford F-250 w/ 6.2 gasser. CEL came on. Code reader shows P0420.. catalytic converter system efficiency is below the acceptable threshold on bank one
Start it running in graph mode for readings...wtf... am I reading this wrong or are the readings for upstream and downstream 02 sensors reversed?
Is it possible the wiring is reversed? Both bank 1 and bank 2 ?

 

[Rambler]

Did you have the catalytic converter up to operating temp? Cats need to be at 600 degrees before they operate correctly. Going to need more info to make a proper diagnosis.

 

[joel2000]

Thought so but maybe not…I’ll try again and see where they graph out after considerable heat up.
Thanks for the question…to be continued…

 

[joel2000]

Road trip to heat converters. Results... not quite as extreme

Did you have the catalytic converter up to operating temp? Cats need to be at 600 degrees before they operate correctly. Going to need more info to make a proper diagnosis.

 

[joel2000]

Looks like they should in these graphs, right?

 

[IfYouDontChewBigRed]

It appears to me you have selected the wrong PIDs. On your graph it shows the current for the upstream sensors but the voltage output for the downstreams. You’re gonna want to see what the voltage output of all 4 sensors is and compare the upstream to downstream. But if you have the 420 fault it is extremely likely you need to replace the Bank 1 Cat.

 

[Rambler]

Bank 1 sensor 1 looks to running on the lean side. The post cat sensors look like they should. I would look for a vacuum leak or something else that is bank 1 to be running lean.

The cat requires enough fuel to burn in the converter to make the heat it needs to work. When the engine goes rich, excess hydrocarbons are stored in the cat. When the engine goes lean, excess oxygen is stored in the cat. Having the correct amount of both hydrocarbons and oxygen is how the converter generates heat to do it's job.

With bank 1 favoring the lean side, there are not enough hydrocarbons being stored in the cat to create the heat needed to do it's job. That is probably what caused the P0420.

 

[joel2000]

It appears to me you have selected the wrong PIDs. On your graph it shows the current for the upstream sensors but the voltage output for the downstreams. You’re gonna want to see what the voltage output of all 4 sensors is and compare the upstream to downstream. But if you have the 420 fault it is extremely likely you need to replace the Bank 1 Cat.

Yep…saw upstream was in ma and downstream in volts but those were the only options given in o2 sensors.

 

[joel2000]

Short term fuel trim at idle and reving a bit

 

[IMDB]

I looked the code up and it states catalytic converter efficiency. Most code readers should tell you what sensors are bad. The last graph shows the downstream o2s are ok, a little high but reading close the same. The upstream o2s the voltage looks low. Do you have 1 or 2 converters? If you have 1 your converter might be failing. Here is the code reader I use. I recently had a o2 fail.