Bad Cat w/02 Sensor OBD Data

Hi Guys,
Trying to figure out a P0430 code on my 2006 double cab that appeared about 500 miles ago.

Truck has 175k miles. Read some other threads, replaced leaking exhaust gaskets on both ends of the cat, no holes or leaks from the cat, no more than half quart oil usage at 4k mile change interval. Fresh spark plugs and timing belt 10k ago. Replaced both downstream sensors with new Denso units.

Some threads mentioned the ECM is looking for readings of 650-800mv. Others said the ECM is looking for variable mv readings as that should correspond to the cat removing more or less oxygen as throttle demand changes so a constant mv reading is sign of a worn out cat.

Below a vid of my live data from by OBD scanner. This data was taken after a 40 mile drive. Turn the volume down as the beeping may annoy some people. As far as I can tell I should not be getting a P0430 code as the B2 sensor (throwing the code) is practically identical to the B1 sensor. Data shown is with two ebay anti-foulers installed. Thanks for taking a look.

Edit: Both upstream sensors were replaced 100 miles ago as well. P0430 has been cleared with OBD, then reappears after about 75 miles of driving.


https://www.youtube.com/watch?v=QMHdRda_cOM

 

Taken from another post with the best advice I've seen from anyone on the topic:

You may want to give it a shot, the code should be telling you which side/bank your problem is. If the code switches to the other side after, you can probably safely suspect bad sensor. If not, chances are something else is up.

Anyway, if it helps, and you haven't seen it, check this out: https://tundras.com/threads/engine-code-p0430-diagnostic-help.65052/

 

Instead of trying to get the O2 sensors further from the stream (it's probably not a fouling issue, unless you're burning tons of oil which has already ruined your cats) use an O2 simulator instead. Nothing saying you have to remove it if it works...

 

There's not much on the forum about 02 simulators. A couple threads about simulators when installing headers, one dude seems to be building his own, another about inserting a resister into the sensor wiring. Do you have a preferred brand of simulator?

 

Problem solved.
I figured I'd try the fouler trick to see if it worked. I started with this one but cel came back.






Then I doubled them but cel came back.




I then read some posts and thought I'd try this one with a smaller hole but cel came back.




Final solution was to stack a short one with the longer, smaller hole, one. Cel went off on it's own after about 100 miles and just passed emissions.

 

Basically what this guy is describing? What's the realistic long-term impact, other than reduced emissions and possibly reduced fuel economy?

https://www.youtube.com/watch?v=ASB_UkCauZ8

 

Sounds like a win-win to me, honestly. Pretty sure all of the emissions in my state for OBDII vehicles involves attaching to the computer, they only use sniffers on OBDI and older vehicles, IIRC, and I know for a fact in my 15+ years living inside the city under an emissions county, they've never looked under the hood once.

I had a rear O2 go bad right after my alternator burned up and got replaced. Thought at first maybe something didn't get plugged in after the alt swap, but came back as O2, promptly replaced w/Denso. But I'm not naive, I'm sure my cat will eventually get stolen, inefficient, or replaced if I ever do exhaust, so tucking this in my back pocket. Although I think rear O2 sims are probably a better option?

 

Same here in Maryland. The emission station attendant used to walk around your car with a dinner plate sized mirror on a stick to see if the emission components were installed in your exhaust pipes. They no longer do that and MD even has self serve kiosks. Just plug in the OBD reader and if no codes you're good for two years.

 

On my 2003, the down stream sensor is not threaded. It's got a plate and 2 bolts. I ordered a simulator, but it's threaded just like the upstream. help?

 

You're gonna have to search around the internet but I'm sure it's out there. Search for 02 sensor flange extension, bung extender. This came up in google images but no link to the website to buy it. Also, since you have a flange, you have the option to move the sensor just outside of the cat, then use a block-off plate with some small holes drilled in it. You will need to experiment to get the right size holes but it is doable. Keep in mind all you are trying to do is reduce the number of oxygen molecules that touch the sensor, thus causing the readings fall back into the programmed limits.

 

Have you scoped the cat to verify its condition?

 

Didn't know that was possible. I did have the cel go out on 2 occasions after driving 20 miles. However the cel came back on on the next short trip. I do have a noticeable odor when I pull into my garage with the engine warm. Hard to describe and it's not the rotten egg smell that I have read about. Fuel economy is 300-320 miles per tank.
Can you elaborate on scoping the cat?

 

Get an inexpensive mechanics camera/ boreoscope off like Amazon, pull the O2 sensor and stick the camera in through the O2 bung. Checking the monolith on the cat could be telling into its performance.

Was the short trip started off with a cold start? Did the engine ever reach OP temp?

Were you at OP temp you think after that 20min drive?

And you have a P0430 code as well, correct?