01 taco with 291.000 miles has been throwing out a PO 420 code

Hi, my name is Steve and I'm new to this forum. Would like to thank everyone in advance for any help with this question. I have a blue tooth adapter on order so I can use the torques app for OBD 2 reading for now I'm just using my basic acton reader. My 01 taco with 291.000 miles has been throwing out a PO420 code. I have cleared it twice and scan tool looks like it will come up again (cat and EVAP are still incomplete). Added some fuel system cleaner in the tank a few times and sea foam sprayed into the intake. The exhaust looks tight, I did have to repair the gasket in between the 2 cats with a double up gasket to get it to seal about a 1-2 months ago before this code started coming up. When I used a laser temp on it the rears of the 2 cats were 100 deg hotter on the rear than the fronts were. Have noticed that the oil level has been a little lower after 2-3K miles less than a 1/3 of a quart. But I know that the valve covers were/are leaking. I installed new PCV valve today (have cleaned it with carb cleaner 10k miles ago and it still rattles) since the truck had the original valve. Oil has been change every 5k miles since new. Last spark plug change at 270.00 miles the plugs color look good no oil fouling. The truck runs and drives fine and the mostly highway mileage is around 18 mpg.The coolant level looks good also changed every 30k also.

 

with that many miles I am sure it is one of your cats that is going south...

 

Prob a bad CAT

 

I was afraid of that, I have 2 cats. Has anyone used Eastern or catco aftermarket cats or recommend a good aftermarket supplier? Also would it be a good idea to change out the upstream A/f and downstream o2 sensor? Does anyone also know what the correct Fel pro gaskes are for this truck and where they go?

 

Welcome to TW

 

My truck just threw this code. I cleared it and it has not come back yet. But when I was asking about it the best thing to do is check for exhaust leaks, do a live data feed to make sure your o2 sensors are within specs, and then check to make sure the cats aren't plugged up or broken. If plugged they can be cleaned. If they're broken they will rattle when you pull it off. I was also told that these trucks only like toyota cats. Lots of people put aftermarket cats on only to have it throw the same code because the new cats aren't quite within toyota specs. There's a guy on here called BamaToy1997. He's a mechanic with his own shop. He answered my questions. I'm sure he can answer yours. Shoot him a pm if you have any other questions

 

I didn't hear anything rattle when I changed the #2 cat front gasket. The blue tooth for torque program should be in tomorrow so I hope I ordered new walker gaskets and hope to look at the o2 sensors graph . I would rather clean the Toyota cats than replace them with aftermarket. When you say clean the cats are you talking about laundry detergent? I ordered the gaskets to remove and replace the cats for a wash. Thank you for the welcome!!!

 

I was told to check everything in the following order. Check for leaks, even the smallest of cracks before the cat can cause problems. Then read o2 stats. After that checked for a clogged or broken cat. You can try to clean it. Am unsure of what to use. Some people actually recommended soaking it in orange juice believe it or not haha. I guess Subaru or some company like that is known for cat problems and this is what the service bulletin says to use haha. If it's broken it wil have holes in the honeycomb when you look in, and May or may not rattle. The best thing you could do if it's broken is A) get a new toyota cat, but you will pay for it. It's expensive. B)find a used cat at a junkyard, just make sure it looks good inside. 3) delete the cat run a URD rear o2 sensor simulator and just run some pipe in place of the cat

 

BamaToy1997 definitely knows his stuff if you have questions. Welcome to TW btw!

 

Can anyone help with this similar issue?

https://www.tacomaworld.com/threads...nverter-issues-0420-check-engine-code.376612/