Clogged Cat

Hi All,

Dumb question but my father’s 2009 keeps getting the P0420 code (Catalytic converter below threshold).

Currently the truck struggles to go above 3000 RPMs and is sluggish.
Is it OK to drive like this for a while or should we swap out the CAT?

Thank you in advance.

 

could it be a sensor?

 

Like a crank sensor?

I’m not sure how to rule it out.

 

If the truck isn't running up to snuff I don't know what to tell you.

I struggle with a P0420 but it doesn't affect the drivability

If you can get your 02 sensor out you can use a borescope to see the condition of the Cat. You should look for holes in the exhaust as well.

I have done a list of things so far to treat mine. They haven't totally gotten ride of my code but the truck does run better.

spark plugs
MAF sensor
Air Filter
gas cap
fuel/Cat cleaner (Lucas and Duralast)
PCV Valve

All these cleared the code for a month or two. today I seen it pending again on my scan tool...so it goes.

There is a spark plug fowler 02 sensor cheat that will get ride of the code but won't fix the problem if it is more serious.

Good luck.

 

If the only code you are getting is P0420 and you can't get over 3000 RPM, I'm guessing the cat is REALLY plugged up. I just swapped my Cats out for that code. Other than the CEL, I felt zero difference in drivability. I checked O2 sensors first, both were good, then took to trusted shop that said it was time to replace Cats.

 

Doubt theSe are related. Clogged cat slowly eats into performance over a long period of time. Most causes of p0420 will not cause the degradation on performance above 3k.

sorry but the sluggish performance could be a lot of different things.

 

Typically this is a fuel pump issue.

to confirm a cat is clogged the easiest way without a vacuum gauge is to remove the upper o2 sensors and drive it.

 

Curious, what does that do? What would you look for after removing it? Do you mean to simply unplug the sensor, or actually take it out and drive with exhaust escaping the hole?

 

Yes, it is enough to confirm if the cat is plugged if the sensors are out and creating a leak.

 

Be very careful doing this, do not run it long and note what is anywhere near the hole as it will quickly melt any plastic or wiring that is nearby.
I'd recommend using a backpressure gauge installed in the O2 port to check for a clogged cat.

 

We had a Ferrari 360 that had plugged cats, I told my boss they were plugged from a leaking injector, but nope, he wanted to drive it. I joked that he should bring a fire extinguisher.

5 minutes later I got a call to bring one. The engine bay caught fire.

You're right its not ideal, and should only be used for free reving to test. Back pressure gauge is the right move. Or an infrared gun to measure temp differential on the cats etc.

I still think this is a fuel delivery issue.

 

Yea I've had a few come in the shop with the o2 sensor out because the cat was plugged, needless to say everything in the area of the hole was melted/destroyed.

I'm typically using AFR & O2 sensor feedback and/or a VE test for a low power complaint to determine if I'm going after fuel delivery or checking for a restricted exhaust.

 

I've seen maybe 2 cats plugged on toyotas, very rare.

My first was a G35 and I even made a youtube video on it I was so proud.

https://youtu.be/vw1pRDuwP6w?si=zm9G-jsLeo21htEy It was a leaking injector which you could hear. So we removed the cat and took it out back.

 

Yea typically when they are plugged it's the result of a misfire or fueling issue that was ignored but I have also seen where the primary cat will come apart and plug up the secondary one as well.

Can't recall seeing a Toyota with plugged cats but we don't get too many Toyota's in where I work, most of the ones we do get in are cars. Very few Toyota trucks come in, mainly work on GM, Ford, & Dodge/RAM.

Had an F250 a couple weeks ago that had the kitchen sink thrown at it (and several problems built in as a result) by another shop for a low power issue, once the issues caused by the shitty parts they put on were resolved a quick test drive screamed plugged exhaust to me. Quick backpressure test showed bank 2 was completely plugged, new cats and verified proper fuel control and no misfires and it's good to go again.

Moral is do the tests to verify a bad part before replacing parts.

 

Big thing is asking why its plugged for sure. Like you said AFR is a super important thing to watch.

I had one at nissan, it was clearly plugged, but something seemed off, so I used to lift rails and pressurize them, one injector was spraying erratically but not causing a flash.

I had the advisor call the customer asking if there was any fuel issues. The customer forgot to tell us, a battery tipped in his bed, it ate through the bed, into the tank and insurance paid for everything, but months later the fuel system finally showed its issues.

I used to be such a observative tech. Dont ever give into flat rate habits DM93 lol.

 

I'm not flat rate, I don't think I could work on flat rate. I'm too picky with stuff to be super efficient although I can meet or beat book time on alot of stuff.

My boss and co-worker aren't as particular with making sure things are right or doing all the testing which can be kind of frustrating at times but it's still alot better than some of the other shops in my area.

 

You could pull the y-pipe and inspect the rears of each cat. Might be obvious.

Some light taps on the exhaust with a deadblow hammer, near the cats, might let you hear a rattle. Sign of loose cat material.

If you're feeling adventurous, with the y-pipe off, you could feel for exhaust flow differences.

https://youtube.com/shorts/O7-ZylA7Nuc?si=NoxTYZcsHzvZfO_o