Pesky P0420 code Techstream freeze frame data

dont raise the rpm just let it idle. they should switch at the time time im wondering it the increased rpm is forcing it to.

 

Ok, I'll take it out for a spin today to warm up and then I'll rerun the test when I get back home, just letting it idle.

 

Disregard the old tests, I may have had the +/- 12.5% rich/lean backwards.

Here's the latest test. There's a -12.5% button, a 0% button, and a 12.5% button.

On this screenshot, I show the truck just idling and then I hit the 0% button and that is when it switches. I left it just like this for about 45 seconds.



On this screenshot I unclicked the 0% button and let the truck idle.



On this one I went from idle to the 12.5% rich condition.

 

FWIW, the CEL came on a couple days ago. Again, it had set the code but the CEL wasn't on. I confirmed the bulb was good and left it just like it was, i didn't clear the code. The CEL was on yesterday. Cold front came through yesterday/last night and it's in the 40's today. The CEL is off and the P0420 code is "current" and "stored".

 

The last photo shows it failed. I point out where you can see it. Right when you switch to rich you can see both a/f sensors switch immediately and your bank 1 oxygen sensor also does meaning that cat is not filtering any nox. there always has to be a delay it can be 1 sec or 15 there not real standard its all calculated by the computers algorithms, but we do know there has to be one.

 

AhHa! There it is. From your explanation at the very beginning I was looking for the lag and couldn't see it. I had the test messed up originally but I can see it clearly now. @stefanlg55 thanks again for hanging around and interpreting these test values, it's much appreciated. I had already ordered a magnaflow passenger side replacement that should be here on monday and I'll tackle the replacement this coming weekend.

Here's a blowup of the switch showing the delay.

 

not a problem i enjoy these kinds of challenges lol. On the yellow line you can see the filtering action of the good cat, the line is not going directly rich its takes a little time then when the cat becomes fully saturated the oxygen sensor will start to read that and go full rich.

 

Thats great info to know and explains whats going on perfectly. I'm one that wants to learn why and not just that the cat is bad and to change it. I had the tools, just didn't know how to read the information.

I started down this road as I have been watching the South Main Auto channel on youtube. That guy is a diagnosing savant.

Once I get it changed, I'll run the test again and post the results.

 

That would be great id like to see a comparative test on a magnaflow exhaust oem vs aftermarket. im curious if the aftermarket will show better results. check out scannerdanner on youtube too, he gets into alot of the details on diagnostics.

 

I'll check out scannerdanner, thanks for the heads up.

 

I had to return the Magnaflow manifold I ordered. They do sell a factory replacement, but I ordered the wrong part number. So I decided to replace it with a Walker version. Finally got it installed yesterday and the truck sounds smoother/quieter and runs better. I did not see any signs of the original converter being bad. I've only had a chance to drive it a few times but no SES light yet.

A couple weeks ago I did have the P0420 and P0430 code come up at the same time. It was the first time the P0430 code has been set. I have the drivers side manifold out for delivery today and will replace that in the next couple of weeks.

 

@stefanlg55 I just finished up changing out the left side manifold with another Walker and new A/F sensor. So, each side now has a new manifold and A/F sensor. And we wait... hopefully no codes.

 

Nice you deff should be good now. have you tried testing it after to see what the new results are like?

 

I haven't tried rerunning the tests. It was setting the code so quick before the change, so no code equals working fine to me. I'll rerun the test over the weekend. I did notice the exhaust is quieter and the truck runs smoother and doesn't have a lag in power between shift points.

 

Hi there, I’m new to the forum and I just saw this thread and I’d thought I’d put my 2 cents in. I briefly looked at some of the posts and pardon me if this has already been said. With 130k on the odo and a P0420 code.... You need a Cat. P0420 is a standard OBD2 code for Catalyst Efficiency Below Threahold. If it’s a stand alone code.... replace the cat(The computer measures the valves between the front and rear oxygen sensors and thus determines the fault) If there are other associated codes ie lean codes or 02 Sensor codes...fix the vacuum leak or replace the O2 Sensor and REPLACE THE CAT. I would install a factory Toyota unit and get another 130k out of it. Anyway from my experience once that code comes
On..its time for a Cat. Anyway just trying to help. Good luck