The p420 codes keeps coming up

so the damn p420 code keeps coming up on my scan gauge on my 00 1st gen where do I start to fix it , it's Arizona registered , so I'm thinking start at the O2 sensors any input ?!!!

If O2 sensor don't , I read a thread that said to check the exhaust manifold gasket , then move to getting to cats HELP!

 

I dumped a bottle of cataclean in my fuel. Worked for me. Have passed smog test for 2 straight years since.

 

420 usually is the downstream sensor. Many vehicles it canbe disabled or bypassed as it doesn't control anything in the engine. It just makes sure the cat is working.

 

the p0420 code on my 2nd gen, is a lean code. it is saying the o2 sensor is reading low. a lean code just means your getting to much oxygen in the exhaust stream and not enough fuel. check for exhaust leaks before the sensor. on my taco, i can clearly see the crack in my manifold and exhaust gas leaking.

if not that check your fuel delivery system, something could not be delivering at the specific amount.

 

If you have have a 3rz check your headers for cracks.

 

Its not a lean code, its the generic catalyst efficiency code. The front sensor checks and adjusts for air/fuel, the rear checks that the cat is working correctly.

 

Cat is bad. Buy URD's O2 sensor signal conditioner for $90. Or a new cat for $3k

 

That's illegal for street vehicles in California and a new cat doesn't cost 3k. Unless your buying it from the stealership.

 

It is a little over 3k for oem cats. If you use a cheaper after market you will regret it. Light will stay on and you will wAste your money. Try the cataclean if cats are the problem it will get you through a smog then you will have time for the right fix.

 

Well if you don't feel like spending over 1 grand OP. Call "The truck shop" in San Diego and ask what catalytic converter they recommend or would use for your truck. They are great guys and have great knowledge on Toyota trucks.

 

I know they are illegal but I can't buy a used car in NYS (follows CARB emissions). Dealer was outrageous. $90 sim, lights out, passed inspection & everyone's happy.

Dealer said the cats precious metals have been burned off that's why the readings trip the code

 

You passed the sniffer Aloe?

 

P0420 is always, always a catalytic efficiency error. You're rear o2 sensor is deviating more then 15% from 0.5v or in relation to the front o2 sensor. Basically means the catalytic is not doing its job. You can see this by comparing the bank 1 and bank 2 sensors on a scanner. Just like others said, ignore it until it's time to smog the car, then go get Bub down the street to put in an aftermarket cat.

 

I bought a new o2 sensor and that fixed mine. I wasted time and money on the urd sim, it didnt fix anything.

 

Old thread but doing a search for my P420 code.

Got URD's O2 sensor on mine, have had it for years. The cat was stolen and at the time it was epidemic so I put a straight pipe in as to not be victimized again. With that said, I just got a P420 this morning so I will most likely have to replace the sensor again. I replaced it a few years ago. The URD is a good idea but not foolproof.

 

You can test the rear Catalytic converter by using a back pressure gauge. Remove the O2 sensor, install gauge in its place, start vehicle and read gauge. If it reads greater than 3 (IIRC), then the cat is bad, if less, then the sensor is bad. Dont just throw money at it, test for faulty parts first and then buy the part you need.

If it ends up being the cat, here are some Direct Fit options from AutoAnything for you:

https://www.autoanything.com/exhausts-mufflers/20A50522A1.aspx?N=4294956333+4294957132

If you decided to order from the above site, be sure to get a quote from the AutoAnything thread in the Deals/Coupons section. You'll get an answer back fast with the best price. You can also find reasonable prices on Amazon as well so be sure to shop around.

Happy wrenching!

 

Forgot to quote yor post so you'd get notified; read my post above.

 

It’s just reminding you