Toyota PO420

[Supra725]

Over the weekend, my Check engine light came on..... Today, I went to my mechanic and had the code to be checked.

it turned out to be a PO420...

Is something about my catalytic converter.. What could it be that would cause this problem?

Could the 420 be bad o2 sensor?

Or do i have to replace the entire thing?

The stealership wants 1300 for just the catalytic converter...

Have any of your guys ran into this problem?

What is your solution to this problem?

Currently, I have 190 k on my 4runner..

Some of my friends told me to sell the car and get something else....

I would love to get a new 4runner but I rather keep it with the economy like this...

thanks.

 

[shootmymime]

lol, i pulled a p0420 today on a 97 camery! all we did was clear it and we sent the car on its way! try this....



put the key to the "ON" Poisson,

open the hood

find the fuse block

remove the fuse ".... i cant fricking remember!"

let me do some searching... hold on.... i can solve this.....

EDIT-
i belive it is called the "ECU" fuse,

pull that and WAIT 30 SEC!

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

and so on....


28.
29.
30.

alright out it back in, start your car and see if the check engine light is on

 

[Victor]

lol, i pulled a p0420 today on a 97 camery! all we did was clear it and we sent the car on its way! try this....



put the key to the "ON" Poisson,

open the hood

find the fuse block

remove the fuse ".... i cant fricking remember!"

let me do some searching... hold on.... i can solve this.....

EDIT-
i belive it is called the "ECU" fuse,

pull that and WAIT 30 SEC!

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

and so on....


28.
29.
30.

alright out it back in, start your car and see if the check engine light is on

It's the EFI fuse, remove that for 30 seconds.

Drive it and monitor it, if the same code comes back, look into it further.

I would honestly get a 2nd opinion (the dealer), there`s in depth testing with the diagnostic manual.

I would look into that first, I would hate to have you replace the cat and have that same code come back. MAKE SURE!

 

[blk runner00]

if pullin the fuse doesnt work you can disconnect battery for 30 seconds and then reconnect. if the code returns i would look into it futher. i would be willing to bet that you have a front o2 sensor going bad. as this happened to me. you may have to have a shop put it on a scan tool to see if the sensor is getting lazy(going bad) and giving a inacurate reading.

 

[shootmymime]

THATS WHAT IT WAS! EFI!
THANKS!

yes everything that was said is great! i would like to add... if the code comes back i bet its a O2. how an o2 works, it sends information to the ECU as an example the numbers 1, 2, 3 and so on, then computer reads the numbers.

the computer has been programed to only accept numbers 3-6 (this is only an example i have no idea what the perimeters are on the ECU) and if that number the 02 sends dosn't fall into the specific range (3-6) it throws a check engine code,

but by clearing the code it will flash the computer and tell it the code is no longer a problem, but if the light comes back on, there is an active problem in the engine and not just a glitch that set the check engine before.

 

[Supra725]

Is there anyway I can check to see if the o2 sensors are bad?

like Napa?

I checked the haynes repair book and it didnt say anything on the catalytic converter, however I haven't read the part about the o2 sensor though.

 

[shootmymime]

well i believe there are 2 o2 sensors on the 4runners, 1 b4 and 1 after the cat. they measure how much fuel, exhaust, co2, and other chemicals are escaping

 

[Victor]

Is there anyway I can check to see if the o2 sensors are bad?

like Napa?

I checked the haynes repair book and it didnt say anything on the catalytic converter, however I haven't read the part about the o2 sensor though.

You will only be able to check the resistance of the heater circuit of the Air Fuel sensor (1st O2 sensor) and the heater circuit of the 2nd O2 sensor.

This can be done by using a multimeter, specs should be in the manual if there are any.

If you wanted exact numbers (running the engine, check fuel trim % you'll need a scanner.

Honestly, if you can afford it just have the dealer look at it and that way they'll give you a definite answer.

Basically, the first O2 sensor (Air/Fuel sensor) as Toyota calls it, it measures how much air and fuel is entering the catalytic converter. The 2nd sensor measures the exhaust AFTER the cat to determine the efficiency of the catalytic converter.

 

[Stick Figure]

the 3rd gen has one o2 sensor or a/f sensor, the second "o2 sensor" is technically a catalytic efficiency sensor. This is the one that the P0420 code refers to. This means that either your cat is failing or the sensor is. For all the info on testing the sensors, you can read up on it http://www.autoshop101.com/forms/h37.pdf
there. You will need either a decent scan tool, yes a scan tool, not a code reader. Or have access to an oscilloscope.


You do have a good chance that you can reset the ECU and be fine for a while, but set a few $'s aside for the day that you can't reset the code.

 

[Supra725]

the damn code came back again within 2 days.....

What can i do guys?

Either replace it for around $1500 or something?

What did you guys do when yours had that code?

thanks.

I didn't expect the cel to be coming back that quick......

Is kinda of hard to deck out 1500 with the economy being in this state...

 

[shootmymime]

its not going to be your cat! so donw worry about that $1500. all it is, is one of the o2 sensors, i think they are 40 bucks. there are many writeups on here about them, try the search bar.

P0420 Catalyst System Efficiency Below Threshold Bank 1

does "bank 1" mean its the 1st sensor?

 

[Supra725]

PO420, according to the Haynes repair menu....

Is Catalyst system efficiency below threshold(Bank 1)

There is 2 sensors on the catalytic converter.

1 is before the cat and 1 is behind the cat.

Is it the first sensor that is going bad?

Does Bank 1 = sensor 1?

 

[blk runner00]

bank 1 sensor 1 is the front o2 sensor. buy a toyota one NOT an aftermarket one. im not all about dealer parts but this is one of the things i always say go oem. mine was just over a $100 but by time you buy a after market one and it last 6 months if that and you need a new one you could have got the oem and be worry free. by the way you can get it on partznet.com for $107 plus shipping also get gasket and replacment 2 nuts to make life easier.

 

[Stick Figure]

on a system like the 3rd gen 4runner there is only one bank so bank one sensor one is the front air/fuel sensor the bank one sensor two would by the catalytic efficiency sensor. The second bank is for cars w/ 4 sensors, which would be most newer vehicles.

The other option out there is to put a simulator http://www.o2simulator.com/ cheaper than a stock sensor, but not exactly legal.

 

[Supra725]

So the code 420 is bad o2 sensor correct?

If so, I'm going to give the dealer a call about the front o2 sensor....

blk runner00, had this happened to you in the past?

How much will it be for the front o2 sensor?

sensor 2 or bank 2is the catalytic sensor?

I'm very noobish when it comes to the car emission system.


thanks.

 

[Stick Figure]

bank 1 sensor 1 is the front

bank 1 sensor 2 is the rear (after cat)


bank 2 sensors are not found on the 3rd gen so you don't need to worry about them.

the code p0420 is a "catalytic efficiency below threshold" this points to either the catalytic converter being bad OR the "o2 sensor" that monitors it (b1s2). its more likely that the sensor is bad, but the first thing i would do is physically look at things under the truck. Check for damaged wires etc ( i threw this code once after going through a good size "puddle") if you don't see any damage to the wiring or any exhaust leaks, then. you can either gamble on the sensor and buy one, or pay a shop to finish the diagnostic on it, to be sure its the sensor and not something else, but this is probably going to cost almost if not more than the sensor.

hopefully that clears things up

 

[Supra725]

Wow, I'm such a noob....

I asked for the price where it was already posted lol.....

I went to my local napa and asked for the front o2 sensor.... They wanted $200 + for it.

Over the weekend, I did went over a mud puddle.... Would that led to setting off the cel?

Thanks for the info Stick Figure....

The code pulled today was the same one that was pulled on Monday and it was PO420....

I will check my 4runner in the morning...

What do you mean by gamble??

I took it to my mechanic and he talked to his partner about it.... He said changing the o2 sensors might not be sufficient enough....

Since my 4runner has almost 200k miles on it...

I don't believe there are any damages
around the exhaust area.... But I definitely look into it first thing tomorrow morning..

partznet carries oem factory parts correct?

thanks.

 

[beer-toe]

yes i know this thread is old but rather bump then a start a new... i have the famous code.. i just want to make sure im buying the right 02 sensor for my truck, since i cant match up the part numbers on denso website..

I have a cali truck, v6, auto and it has two cats.

is this the right 02 sensor for me before i make the purchase?


denso 234-4153? amazon has them in stock for around 50$

 

[Road Bull]

Have you checked your Mass Air Flow Sensor?

Had the same P0420 code a few weeks back in my 2002.

I cleared it by doing what was performed in the video below. Eight bucks, and change.

https://www.youtube.com/watch?v=aHGZF-uCdpI

It didn't go right away. But after about a day and a half, or two days, it cleared itself. Start with the easiest fixes, (also the cheapest), and work your way out from there.

 

[MONTYMTB]

yes i know this thread is old but rather bump then a start a new... i have the famous code.. i just want to make sure im buying the right 02 sensor for my truck, since i cant match up the part numbers on denso website..

I have a cali truck, v6, auto and it has two cats.

is this the right 02 sensor for me before i make the purchase?


denso 234-4153? amazon has them in stock for around 50$

Nope, you need 234-4261