P0420 Low Catalyst System Efficiency (Bank 1)

Hey all,

I've got an 05' TRD Off-Road with a 4.0L, 6-speed, 4WD and have gotten the P0420 code repeatedly after trying multiple fixes including O2 sensors, checking for exhaust leaks and running some SeaBreeze through to try and clear the code. Each time i've scanned and cleared the code it has come back within a few miles of startup and driving.

The truck is coming up on 180K so I am at the point that it is just time to replace the cat altogether given the mileage and its the original one.

What have your experiences been in replacing the cat being as it and the exhaust manifold are all one piece? Any tips, suggestions, etc. before I purchase and go at this? Checked with a shop just for an idea and got quoted at $1800 so that's not coming out of my pocket.

Also, any suggestions on a particular cat for my truck?

Thanks much

 

What's your feelings the spacer technique? Won't fix the problem but gets the code to go away....

https://www.autozone.com/ignition-t...dorman-spark-plug-non-fouler-42002/720789_0_0

I've got mine ready but can't get my 02 sensor off...

 

Experiencing the same issue however I have yet to attempt anything to resolve the issue. Friend who is mechanic told me the O2 sensor needs a spacer. Is this the best way to go as first attempt at resolving the code?

 

I did the Cataclean and the Lucas fuel additive. They both seemed to work for well over a month but eventually the code came back. I believe my issue was caused by a misfire I had at the same time. That code has not come back and I don't currently have the P0420 either so that's good. Also I don't live in California anymore either

 

What tools are needed to get the O2 sensor off without removing the cat?

 

This is a pretty good video I found....

(104) Best Technique For Removing Stuck O2 Sensors - Don't Gall The Threads! - YouTube

 

Do you have any misfire codes?

What are the fuel trim readings while driving around normally?

How did you check for exhaust leaks?

 

I have had the exact same issue with my 05 Tacoma 253,000 miles ... 0420 code, had O2 sensors replaced, mechanic said my cat was fine. The CEL went off for a couple days after oxygen sensor replacement, came right back on tho. I have also used Cataclean on it a couple times. 1st use cleared the code for about a month, then it popped back up. My mechanic was able to get the truck inspected right after replacing the O2 sensors so I have a valid registration sticker, but I feel like I'm gonna have to keep jumping through hoops with this to get the truck to pass an inspection each year. Idk what to do to resolve the problem at this point. Truck runs great tho.

 

OP here with an update.....

I've recently been having a rough idle at start up and CEL blinking at times. Typically smooths out. Occasionally need to shut truck off and restart and its fine. Code was for misfire on cylinder 6. Going to change all my plugs since its time anyways and get a new coil pack just in case. Then clear codes and see if the problem/s go away for good.

I have not tried the spacer but have heard its an easy workaround if you need to pass emissions.

The o2 sensors right off the manifold are a pain. I ended up pulling the wheel off on both sides and was able to get an angled 02 wrench on and get them both out.

(https://www.autozone.com/test-scan-...SY1Ht83sbivDr0sJY5kaAnMwEALw_wcB&gclsrc=aw.ds)

Drivers side is a pain in the ass with more in the way but it is doable.

Update coming after I take care of the misfire.

Thanks all for your input and suggestions.

 

What happened?

I’m experiencing the same issue except mine is Bank 2. The truck has 231k miles and I need to fix this & have the truck pass smog before the end of the month.

 

From what I’ve read regarding the 2.7 4cyl, bank 2 fault may indicate a leak prior to upstream sensor and bank 1 fault can indicate either a leak between upstream and downstream sensors OR a failed converter.
** DISCLAIMER**
I’m not a scientologist, just a hack/shadetree mechanic, so correct me if I’m wrong here.

You could start it from cold and use dish soap mixed with water in a spray bottle to do a quick leak check before everything gets hot. Spray the joints and you’ll see bubbles if there’s a leak somewhere.

I have been living with a bank 1 code for a while but now that I just got my emissions inspection notice I have to deal with it. In my case it’s a failed converter, it’s extra crusty. Was planning to just replace the converter itself but on further inspection I have multiple small leaks and all the exhaust connections are rotting so I’m doing a whole system w/converter & both sensors just to make sure it’s handled. I’m only doing the whole shebang because I’m at 190k and planning to have the truck for a couple more years.

 

Guy lied and never updated.

 

What angled O2 Wrench did you use?

My issue is Bank 2

 

Just an update on "NEW CATS" in NC those are now 3k for a 2009 truck.

 

Is that Parts + Labor to have a Toyota Dealership do the work?

 

Yes and I'm not sure if it includes the 02 sensors

 

Chimed in earlier with my experience with this code. I just recently replaced my cat, both o2 sensors, and the full exhaust system. I went with aftermarket components to save $$ which others have advised is dangerous, but so far after I have had no hiccups. I know it’s not a direct comparison because I have a 4cyl, but my cat was about $268, not including the o2 sensors.

For the o2 sensors I used a 7/8” o2 sensor socket from Autozone but you can use a crows foot wrench & ratchet in a more confined space or even sacrifice a box wrench to put in a vise and bend to the angle u need (heat it with a torch first)

 

Hi all,

Way after the fact on this update...

I bit the bullet and bought new cats for the whole truck from rockauto.com. along with the O2 sensors for roughly $1100. Still steep but compared to a shop to just do one for almost $2K definitely the choice to make!! My only hesitation was that if I broke a stud off but dodged that bullet on both manifolds.

With the help of my neighbor who has a vehicle lift and is a former diesel mechanic we changed out all four cats and sensors and its back to running like a champ. Figured if I was going to change one side I'd do both since they were definitely the originals that came on the truck. Altogether it took us about three hours and didn't have any studs break off which was a time saver. Fired it up and put the OBD scanner on and cleared the P0420 and misfire code and they haven't come back on. All in all I saved a fat wad of money making repairs on my own and thank you all for the input you gave. I'll will always look here first for input, tips, and suggestions!! Approaching 200k on the odometer so with regular maintenance I should be good for years to come!

To some of your questions.....I have an o2 socket from Napa and o2 wrench from Autozone but only needed the socket since we took everything off and installed prior to putting back on the truck.

Have a good one!