So, if my P0420 comes back...

T4R_Finally

T4R_Finally

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Installed new O2 sensor. Now it's the waiting game. If I get a CEL with a P0420 again, what's my next step? New CAT, new CATs? Would both CATs necessarily have to be replaced or is the some way to tell which one is bad?

How difficult are they to replace? I've seen people post about CATs being stolen. If they can get be stolen while the vehicle is sitting on a street or in the drive, does that mean they are easy to pull and replace?

If I can change them by myself, what am I looking at as far as cost for parts? Is there somewhere to order the right parts other than a dealer?

Are they bad ones worth anything for scrap? If so, where can the be taken?
 
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Interesting option. So, does it install between the O2S and the vehicle wiring and conveniently hide up there somewhere?
 
T4R_Finally said:
Interesting option. So, does it install between the O2S and the vehicle wiring and conveniently hide up there somewhere?
Click to expand...

Yes it does.

The cat is easy to cut out sloppily with a sawzall... Not so easy to weld back in. The upper one is a real pain, the lower is not so bad.

Yes, the old ones are worth a bit, actually, that's why they get stolen. Your local metal recyclers will take them.
 
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P0420 is the Air/Fuel sensor. Bank 1 sensor 1. I had the same code on my 01 4runner and an a/f sensor fixed it.
 
haddix said:
P0420 is the Air/Fuel sensor. Bank 1 sensor 1. I had the same code on my 01 4runner and an a/f sensor fixed it.
Click to expand...

My AF sensor has already been changed and it was as a result of a completely different set of codes. It sits upstream of the CATs, so how could it possibly report a catalytic deficiency (P0420)? It's the downstream O2S that throws that code.
 
haddix said:
P0420 is the Air/Fuel sensor. Bank 1 sensor 1. I had the same code on my 01 4runner and an a/f sensor fixed it.
Click to expand...

It can be either one. FSM lists 4 possible causes:
1. Gas leak in exhaust
2. A/F sensor
3. Downstream O2 sensor
4. Bad CAT
 
If the URD sims are too expensive, you can always put some spacers on for the time being. I had both my cats go bad (not a clue what happened, but they were almost gone), put some 02 spacers on, and it kept the ECU happy enough. However, I put on the JBA performance longpipe headers, and that threw a code no matter what.

Therefore, your cats may have enough "life" left in them that a spacer will trick the computer for a year or two. If you want to upgrade to some headers, and delete the CATS completely, no spacer will be enough to trick the ECU. Then you'll need the simulator from URD. (I can vouch that it works pretty good so far. Running the JBAs with no cats at all, and no code for a few weeks.)

To build the spacers, go to advance auto (if you order through the website, you can use the big discounts on dealnews . com), and get a pack of the HELP! Spark plug nonfoulers part # 42009.Dont use the washers, and drill out one of the spacers enough that your 02 sensor can screw in, and the tip will fit in the hole. Screw the second one on the end of the first, then put the whole assembly in the 02 port. Should work long enough (6 months-maybe a year) for you to decide on a permanent plan of action.
 
$100 bucks vs. over 10 times that for new CATs doesn't sound too expensive to me and it's plug-n-play. If my code comes back, as long as I'm not noticing any performance issues, exhaust related odors, or sounds related to issues down there, I may give the URD a shot.
 
T4R_Finally said:
$100 bucks vs. over 10 times that for new CATs doesn't sound too expensive to me and it's plug-n-play. If my code comes back, as long as I'm not noticing any performance issues, exhaust related odors, or sounds related to issues down there, I may give the URD a shot.
Click to expand...

They must have gone up, I've been running a URD simulator for 3 years or more.

A
 
Anyone of you guys ever used these Do it yourself o2 simulator - S-10 Forum ?? It's widely used in the Audi community, and seems to work without the cost of an electronic devise. Of course you always want to use them only for the rear o2-a/f sensor.

Disclaimer: This is for off-road use only and should never be used to mask or supplement the sensors which stop the pollution of the air we breath.
 
Jeff4runner said:
If the URD sims are too expensive, you can always put some spacers on for the time being. I had both my cats go bad (not a clue what happened, but they were almost gone), put some 02 spacers on, and it kept the ECU happy enough. However, I put on the JBA performance longpipe headers, and that threw a code no matter what.

Therefore, your cats may have enough "life" left in them that a spacer will trick the computer for a year or two. If you want to upgrade to some headers, and delete the CATS completely, no spacer will be enough to trick the ECU. Then you'll need the simulator from URD. (I can vouch that it works pretty good so far. Running the JBAs with no cats at all, and no code for a few weeks.)

To build the spacers, go to advance auto (if you order through the website, you can use the big discounts on dealnews . com), and get a pack of the HELP! Spark plug nonfoulers part # 42009.Dont use the washers, and drill out one of the spacers enough that your 02 sensor can screw in, and the tip will fit in the hole. Screw the second one on the end of the first, then put the whole assembly in the 02 port. Should work long enough (6 months-maybe a year) for you to decide on a permanent plan of action.
Click to expand...


3rd Gen still has the older flanged style Toyota sensor.

C5010112391ND.JPG


So the non fouler trick won't work.
 
Stick Figure said:
3rd Gen still has the older flanged style Toyota sensor.

.......

So the non fouler trick won't work.
Click to expand...

'01 and '02 have the screw-type rear O2 sensor #234-4261:
234-4261.jpg


but I have not seen anyone report success with it on a 3G 4Runner and I have had my eye out.
 
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