P0420 Check Engine.. Still on after New CAT

[daviddep]

03 4Runner V8 Limited. 220K miles..

Check Engine P0420 Code has been troubleshooting for over a year...

Replaced: Up and Down Stream 02 sensors. Replaced Bank 1 Cat with OEM.

No codes for many months.....

A few days ago, i started car and 1/4 inch hole in exhaust pipe blew out.

Drove a few days before repair with No CHeck engine light...

A few days after repair, Check engine light Back on...
Repair was done downstream from cats and 02 sensors...

Any ideas? Taking back to my Mechanic who I trust for many years... he'll take another look...

Could be a blockage in the repair area? constricting air flow???

 

[hutchison]

03 4Runner V8 Limited. 220K miles..

Check Engine P0420 Code has been troubleshooting for over a year...

Replaced: Up and Down Stream 02 sensors. Replaced Bank 1 Cat with OEM.

No codes for many months.....

A few days ago, i started car and 1/4 inch hole in exhaust pipe blew out.

Drove a few days before repair with No CHeck engine light...

A few days after repair, Check engine light Back on...
Repair was done downstream from cats and 02 sensors...

Any ideas? Taking back to my Mechanic who I trust for many years... he'll take another look...

Could be a blockage in the repair area? constricting air flow???

what the fault is currently saying is when it has less restriction its better. personally id be tempted to try an unrestrictive bacbox within your state regs. is it possible to loosen an exhaust coupling further back to try and recreate the fault clearing.

 

[gaber6]

Did you use aftermarket Cat? I have the same code that I clear every other day to keep my trac control lights off. I bought an upstream 02 sensor and shopped around and saw $300 aftermarket Cats.
I imagine they'd work ok as I added cheap cats to my 79 camaro back in 97 and it passed emissions with flying colors.
I hope it works out somehow

 

[daviddep]

Did you use aftermarket Cat? I have the same code that I clear every other day to keep my trac control lights off. I bought an upstream 02 sensor and shopped around and saw $300 aftermarket Cats.
I imagine they'd work ok as I added cheap cats to my 79 camaro back in 97 and it passed emissions with flying colors.
I hope it works out somehow

I used Toyota Cat. At this point were not gonna recreate an exhaust leak. He's gonna use an O2 adapter for the down stream sensor and relocate it further down.....

Hopefully that will work...

 

[MrSeth]

I had been driving around with the 0420 code for over a year when it came time to pass CO emissions. I used 2x spark plug defoulers/spacers. Eliminated the code, passed emissions, and hasn't been on since! I'd recommend it, it's a $17 fix.

 

[daviddep]

I had been driving around with the 0420 code for over a year when it came time to pass CO emissions. I used 2x spark plug defoulers/spacers. Eliminated the code, passed emissions, and hasn't been on since! I'd recommend it, it's a $17 fix.

Thats what my guy is going to put in....

Today, the light went out... if it comes back on, we'll do it..

Wish i would hve non that before i bought a new cat..

 

[rickashay]

I too had the P0420 code for the last 9-10 months. Finally got tired of resetting the code Everytime I started the vehicle and tried the defouler trick. It has worked flawlessly and haven't thrown a code in 2-3 weeks!

 

[Bluecharter.1]

cylinder 3 compression

My 2002 4 runner has a compression problem in cylinder 3. Im looking for a good mechanic in Houston.

 

[WhiteBoomer04]

Tried the defouler method on sons 2004 2WD. Did not work. Tried to use a single defouler on each and when that didn't work tried to double up. Still unsuccessful. Also tried Katclean (5 bottles) and replacing all sensors. Also checked for vacumn leaks. Sigh.

 

[daviddep]

my mechanic installed the spacer. my check engine light had come back on and stayed on over the past several weeks so we finally did the fix and it went out.

hopefully it will stay out for good I will update this post if it doesn't.

thanks for the spacer advice

 

[duffdog]

I had this issue last month, but didn't want to spend any money and I live in CA and I don't want to run cats at all, so there is no way to pass smog without getting dealer provided cats for $6000... Solution is this: I had a miniature catalytic converter machined that goes inside the exhaust pipe and slips around the downstream sensor and contains legit CA carb compliant cat grid. Smog techs can't see it, computer reads it as a brand new cat even with a straight pipe and its quite easy to tune rich/lean as feel necessary for engine mods without the computer changing your settings. The computer thinks everything is amazing all the time. I may be able to get one of these made, but machining time is not cheap and the steel must be exotic to resist the exhaust temps. PM if interested.

 

[T4Rmiller]

I had been driving around with the 0420 code for over a year when it came time to pass CO emissions. I used 2x spark plug defoulers/spacers. Eliminated the code, passed emissions, and hasn't been on since! I'd recommend it, it's a $17 fix.

any more info on this? are there any downsides?

 

[WhiteBoomer04]

I had this issue last month, but didn't want to spend any money and I live in CA and I don't want to run cats at all, so there is no way to pass smog without getting dealer provided cats for $6000... Solution is this: I had a miniature catalytic converter machined that goes inside the exhaust pipe and slips around the downstream sensor and contains legit CA carb compliant cat grid. Smog techs can't see it, computer reads it as a brand new cat even with a straight pipe and its quite easy to tune rich/lean as feel necessary for engine mods without the computer changing your settings. The computer thinks everything is amazing all the time. I may be able to get one of these made, but machining time is not cheap and the steel must be exotic to resist the exhaust temps. PM if interested.

Can you pm me a quote for this and a potential time frame?

Thank you.
Mark

 

[Toyrundrive]

I too had the P0420 code for the last 9-10 months. Finally got tired of resetting the code Everytime I started the vehicle and tried the defouler trick. It has worked flawlessly and haven't thrown a code in 2-3 weeks!

I had the "pending trouble code" P0420 before i modified my exhaust.

Then I put in new headers, high flow cats, a flowmaster and the old sensors. Took about a week and the check engine light came on with an active P0420 code.

What is this defouler trick? Is it just a spacer for the 02 sensor?

I think I should get a new set of after cat sensors...

 

[Terminator03]

I had the "pending trouble code" P0420 before i modified my exhaust.

Then I put in new headers, high flow cats, a flowmaster and the old sensors. Took about a week and the check engine light came on with an active P0420 code.

What is this defouler trick? Is it just a spacer for the 02 sensor?

I think I should get a new set of after cat sensors...

There is a thread, or threads if search that describe in detail how to mod the defoulers, but essentially you are drilling one out to 1/2” diameter to clear the tip of the sensor, and using a smaller hole on the second one that actually screws into the pipe. By stacking the 2 together, you move the sensor out of the direct exhaust stream, with most of the time fools the computer into “seeing” a reading that falls within the efficiency parameters it needs to see. Many people have to resort to this because aftermarket CATs don’t usually meet the parameters in that location for some reason, and even sometimes stock CATs have the issue as well. URD makes an electronic device to alter the signal, which essentially does the same thing, just at a higher cost. I believe their universal version is adjustable though, so if the spark plug spacers don’t work, then the electronic thing can be fine tuned to get it the rest of the way (hopefully).

 

[ac1617]

At $11 there is no reason to buy defoulers and drill them. Just buy these:
https://www.amazon.com/Wolfride-Uni...ds=02+spacer&qid=1554745695&s=gateway&sr=8-20

Worked on my V8 flawlessly. Cats are bad and I'd get a CEL within 20 minutes of driving. Used these extenders for a month without issues.

 

[Toyrundrive]

What do you make of the fact that I had the pending code before I redid my exhaust? I swapped alternators today and the computer reset has cleared the active code, but the pending code is still there

Pending code comes from the ultragauge