[jjf8]

Read thru about 20 threads on P0420

Here is my scenario,

2000 4runner SR5

WED: Heard a rattling sound on a Shore run. No CEL
THURS. Rattle continues . Throws CEL that Evening, P0420
Fri: Talk to mechanic.. says drive it home, bring to in,
Runs fine all the way home except rattle. No smell, gas milage is normal 85 Miles.

Stop at the house, unload and fire it up, No rattle , purring like a kitten, CEL still on, drive it about 15 miles , rattle is gone,

So after reading thru the threads I have determined I have Cali emissions 4runner by the sticker under the hood. This means I have 2 cats,

see pics below,

154k. Rear O2 sensor replaced 6 months ago Denso.

So this my plan as he can't look at it till Wed,, Small honest busy shop, I'll wait,

Want to buy these parts as a pre emptive strike so repair can be quick.

I realize the front and rear cat shown is not direct fit, welding required, that may or may not be an option. Searching now for a direct fit Front with flange

I know it may be just a exhaust leak, but the rattle has me thinking not,

I'll return what I don't need if any.

Am I on the right track ? Thanx for any info ..

[Steeups]

Originally Posted by jjf8

Read thru about 20 threads on P0420

Here is my scenario,

2000 4runner SR5

WED: Heard a rattling sound on a Shore run. No CEL
THURS. Rattle continues . Throws CEL that Evening, P0420
Fri: Talk to mechanic.. says drive it home, bring to in,
Runs fine all the way home except rattle. No smell, gas milage is normal 85 Miles.

Stop at the house, unload and fire it up, No rattle , purring like a kitten, CEL still on, drive it about 15 miles , rattle is gone,

So after reading thru the threads I have determined I have Cali emissions 4runner by the sticker under the hood. This means I have 2 cats,

see pics below,

154k. Rear O2 sensor replaced 6 months ago Denso.

So this my plan as he can't look at it till Wed,, Small honest busy shop, I'll wait,

Want to buy these parts as a pre emptive strike so repair can be quick.

I know it may be just a exhaust leak, but the rattle has me thinking not,

I'll return what I don't need if any.

Am I on the right track ? Thanx for any info ..

This was my first 4Runner and I still have it with about the same amount of miles. I loaned it to a friend for a while to drive around and he was using 87 octane gas when I generally use premium. As soon as I got it back I checked the fuel cap and topped it of with some premium gas. Light has been off for a month or so now. Not sure if this is a fix for you also but well worth a try.

[calimobber]

I see your in california. Just so you realize those both say non carb compliant. Carbs (California air resource board). Not sure if they will catch that or not but just a heads up.


Also higher octane does nothing for our vehicles. All it does is mean if your running a suer charger or higher compression it wont pre-explode before the spark. Dont waste your money on higher than 87. It has no benefit.

[pokeyman]

I would check RockAuto and buy a bolt on CARB catalytic converter.

[19963.4lsr5]

A lot of times the 420 code is caused by antifreeze.

When was the last time you monitored the coolant level in your expansion tank?


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[jjf8]

Looked into the coolent , everything is fine there.


This all started with a rattle on the truck which went on for 1.5 days and then threw the code and then the rattle stopped a day later. CEL still on.

Will rescan it later today after a quick ride around the neighborhood.

Thnx

[19963.4lsr5]

Just pay attention to it. I had very little antifreeze loss.

I’m happy I was able to use my 270,000 mile cat after rebuilding the engine. I do have a spare cat assembly if I ever need it.


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[TheDurk]

Well, on these trucks it is very common for a P0420 to be caused by exhaust leaks. If the system is factory, the gaskets have pretty much turned to dust. So I would carefully check for any exhaust leak from the downstream sensor back. A new gasket and nuts/bolts costs a lot less than new cats (which may fix the problem, because you will put on new gaskets where they meet the pipes, and you will never know how you wasted money.)

I am still running factory Cali. cats on my '99, but I had to do the gaskets which also meant nuts/bolts.

[TheDurk]

Originally Posted by calimobber

I see your in california. Just so you realize those both say non carb compliant. Carbs (California air resource board). Not sure if they will catch that or not but just a heads up.


Also higher octane does nothing for our vehicles. All it does is mean if your running a suer charger or higher compression it wont pre-explode before the spark. Dont waste your money on higher than 87. It has no benefit.

Where does he say he is in CA? Profile says SE PA.

[jjf8]

Thanx, Held off on the parts order. The front cat looks to be original and the gaskets are def worn. Will start the trouble shooting there.

Thing that is throwing me off is the rattle stopped. Went under the truck, everything is tight. exhaust , muffler etc.

See what happens tomorrow,

Thanx for the input,

[19963.4lsr5]

Look at the rear tail pipe section. When an exhaust hanger rusts off that tail pipe section lays on the frame


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[TheDurk]

Originally Posted by jjf8

Thanx, Held off on the parts order. The front cat looks to be original and the gaskets are def worn. Will start the trouble shooting there.

Thing that is throwing me off is the rattle stopped. Went under the truck, everything is tight. exhaust , muffler etc.

See what happens tomorrow,

Thanx for the input,

Well, it could have been the heat shield on the outside of the cat which is no longer there. If it never comes back, that was probably its last gasp before falling off. Mine fell off a long time ago. If it was the ceramic matrix inside the cat, that's usually fatal for that cat. Here is one with the heat shield:



There is a difference between sheet metal rattling from the cats and pipe against the frame noise which is a lower pitch, almost a rumble, not tinny like the other noise.

[jjf8]

So , we are back on the road,

Car had lived its live half in AZ and half in PA so the frame was exposed to the lovely NE winters for the last 10 years, but frame is solid,

Whole exhaust system from the manifold to the tailpipe was original. Muffler was shot, tailpipe was shot, front cat was shot. At this point I replaced the whole system to avoid any issues down the road in case the rear cat decided to go. Prevenitive, only added a couple hundred to the fix.

Went to Rock Auto ordered direct fit front and rear cat CARB compliant, and full muffler/pipe etc kit.
Went with Eastern. Got the 2 Denso O2 sensors as well. $875 and change delivered.

Had to drill out the exhaust manifold bolts as expected, but the whole thing went right in and fits like a glove.

$450 for the install.

truck runs much different, has more pep, just feels better.

And of course , while up on the lift, I saw I have a small leak starting on the front axles.

Took a look with the mechanic and I'm good for a bit, but will adress it before the winter. Not my daily driver. Its 20 years old, things are going to need to be replaced and I maintain my vehicles, its been problem free for almost 2 years. Can't complain.