This Check Engine Light Is Killing Me

Solidape said:
It's the easiest o2 sensor for us to replace.

https://www.amazon.com/dp/B0016NBBQW/_encoding=UTF8?coliid=I3GTMFSUNZQWE4&colid=38TENEECPGIB1

For the next few days, crawl under your 4runner and spray pb blaster on the o2 sensor threads. When the time comes, use an o2 socket on the sensor along with a breaker bar and replace the sensor. Reset the computer and go at it. Fixes it most of the time.
Click to expand...


Just replaced the rear sensor and drove about 15 miles. The check engine light came back on...Darn. Still reading the p0420 code. Also felt like I noticed a slight sulphur smell at certain times.

Any ideas guys?
Thanks
 
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I got rid of me Cat code with a bottle of Cataclean from the auto parts store. 130 miles after adding it the code cleared on its own.


Sent from my iPhone using Tapatalk
 
It was likely done-in by running fuel rich exhaust (read misfire) into the Cat. They don't last forever but fuel rich exhaust just kills them. You are asking the right question because you don't want to replace the cat just to kill it again. I don't think evap system issues harm the Cat. You need to fix the root problem....maybe that has already occurred?

Buckaroo
 
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Buckaroo said:
It was likely done-in by running fuel rich exhaust (read misfire) into the Cat. They don't last forever but fuel rich exhaust just kills them. You are asking the right question because you don't want to replace the cat just to kill it again. I don't think evap system issues harm the Cat. You need to fix the root problem....maybe that has already occurred?

Buckaroo
Click to expand...

Thanks Buckaroo, The Evap monitor has still not set even after 400 miles and I was just making sure that it couldn't be my problem. Wouldn't a misfire be caught with the scanner?

Side note: Can anyone additionally confirm that an Evap issue cannot harm the catalytic converter?

Thanks,
Charlie
 
Deere9798 said:
How about an exhaust leak before the 1st cat? could that have been responsible?
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I would say yes, perhaps. Exhaust leak in front of the first O2 sensor could draw oxygen into the exhaust. The sensor would see this additional oxygen as indicating not enough fuel present to burn all the oxygen so the ECM would add more. The exhaust then would be rich in fuel entering the cat which could damage it. I think, however, that you would have very positive fuel trim which would set a code.

Up to this point, we have been assuming that the P0420 is being caused by a bad cat. The FSM identifies other reasons which should be excluded before indicting the cat as follows:

1. Gas leakage on exhaust system
2. A/F sensor (bank 1 sensor 1)
3. Heated oxygen sensor (bank 1 sensor 2)
And Finally....4. Three-way catalytic converter

One thing you can do to check cat efficiency is check it's temperature using a non-contact infrared thermometer. It should be a lot hotter than the exhaust gasses entering it if it is working properly - operating cat temp is in the +1200F range. It can get way hotter if there is lots of unburned fuel getting to it and eventually the honeycomb melts (=dead cat...can sometimes plug). If it is dead, it is no hotter than exhaust gas. So, using the non-contact thermometer, the temp of the exhaust pipe right at the discharge end of the cat should be higher than the pipe entering the cat after the engine has been running a while.

In case you are curious (like me), short video on how cats work....
https://www.youtube.com/watch?v=rmtFp-SV0tY

Forgive me if I rambled on.....

Buckaroo
 
Deere9798 said:
So I think I am going to need a new Cat but what made it go bad to begin with? Could a bad VSV have ruined it?
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I may be a little late to the party on my response but, I would investigate the cause of the P0171. That is a vacuum leak. Your engine is leaning out, the computer is dumping more fuel in to compensate. That I think is the root cause of your P0420 & cat problems.
 
I have been super busy for a while so I have not been able to provide an update, however here it is.

I recently replaced the spark plugs and the fuel check valve and VSV. The fuel check valve and the VSV seemed to take care of the EVAP codes, however the P0420 continues to return. Here is a list of what has been replaced:
  • Front Catalytic Converter
  • Front 02 Sensor
  • Rear O2 Sensor
  • MAF
  • Spark Plugs

I feel like I am out of options... Thanks for your ongoing guidance and help.
_Charlie
 
Sorry that I have nothing to add right now, I'm just starting to chase down the codes on my new-to-me '01 runner. This is one of the codes that has shown up on mine as well, so I was hoping that you might have stumbled upon the root cause. I'll post up when I tackle mine if I find anything that you haven't already covered.
 
2ndhandyotaman said:
Sorry that I have nothing to add right now, I'm just starting to chase down the codes on my new-to-me '01 runner. This is one of the codes that has shown up on mine as well, so I was hoping that you might have stumbled upon the root cause. I'll post up when I tackle mine if I find anything that you haven't already covered.
Click to expand...

I have a very similar situation and I'm trying
to narrow down the culprit.
I'll follow up with more info.
 
You could take your 4runner into a Toyota dealership and have them diagnose the issue and then fix it yourself. This will keep you from continuing throwing parts at it.

I get to situations like this with my jeep and 4runner. Sometimes I wave the white flag and allow the pros to hook up their specialized machines to figure it out at once so I'm done with it.

I just got done chasing a evap leak on the jeep and it was a headache. I found the issue by luck.
 
Mudeprived said:
You could take your 4runner into a Toyota dealership and have them diagnose the issue and then fix it yourself. This will keep you from continuing throwing parts at it.

I get to situations like this with my jeep and 4runner. Sometimes I wave the white flag and allow the pros to hook up their specialized machines to figure it out at once so I'm done with it.

I just got done chasing a evap leak on the jeep and it was a headache. I found the issue by luck.
Click to expand...

This is what I'm leaning toward after today being told two
different codes from two parts stores. They did both share
the same general theme of fuel/air/sensors.
 
2ndhandyotaman said:
Sorry that I have nothing to add right now, I'm just starting to chase down the codes on my new-to-me '01 runner. This is one of the codes that has shown up on mine as well, so I was hoping that you might have stumbled upon the root cause. I'll post up when I tackle mine if I find anything that you haven't already covered.
Click to expand...

Thanks, it seems like this problem is far more common than I originally thought. Even though I can do the work myself, it feels like I am continually throwing parts at it with minimal results. I just wish I knew what was wrong. Hopefully one of us finds something so that we can figure it out together.

_Charlie
 
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