Cheap potential P0420 P0430 Catalyic Converter Efficiency Fix
 

Hi All,

A little background from me. I am an ASE certified tech of 16 years. I just picked up a 2004 4Runner v6 to have a little fun with on the cheap. I decided to give it a few weeks of driving to give it a proper shakedown and see what it needs to get back up to snuff before I dump some money into fun things.

I am glad I did because after my first longer drive (I work 3 miles from home)...I came back to the shop with P0420 and P0430 codes.

Shame on me. I did scan it at the shop prior to purchase but in my haste I did not check to see if monitors had run. I am fairly convinced the PO cleared the codes and knew I wouldn't likely complete a drive cycle on my road test. He was right.

So here we are. I have codes for both converters on a Cali emission car. Great.

Not 100% convinced I needed cats, or knowing how long this problem existed prior to my purchase. I decided to put 2 downstream O2 sensors in and see what happens. They looked old, old enough to be original. So I swapped them out. I was happy as at first the CEL stayed off. But within a day or 2 it was back. Frustrated I started researching CARB compliant Catalytic converters for the car. Not shockingly I was unhappy with the cost.

Upon installation of the O2 sensors I did notice the flange for the Cat was rusty and potentially leaking, even if just slightly and not enough to make the vehicle loud or smell exhaust in the cabin.

If you've been reading waiting for the fix portion here it is

I got a gasket that goes between the cat and y-pipe for each side.

a little heat to the nuts and it all came apart easily. Once apart it was clear how smoked the old gasket were! The driver's side didn't look all that bad before taking it apart.

I replaced the gaskets and drove the vehicle for 2 full drive cycles. So far so good. I did check the monitors and and catalyst monitors did pass. So fingers crossed that it doesn't come back but I hope this post help anyone struggling with Catalytic Converter efficiency codes.

If anyone has these codes I highly recommend checking the conditions of these flanges/gaskets. The proximity of the sensors to the flanges makes it easy for intrusive air to affect the readings.

Cheers,

Pics below

Could you add the part number here if you have it?

I used a Napa gasket which was "EXH 31332"

I will repairlinkshop.com to get the OEM part# in a little bit and edit this post.

So the OEM part appears to be 90917A6005

But the Toyota diagrams suck to pull gasket numbers as they aren't shown in the illustration.

nice!
would go check mine

Thanks for posting this!!!

Checking and fixing exhaust leaks should be the first step.


Sent from my iPhone using Tapatalk

Nice.. Keep us updated when and if codes comes back.. I am fighting a 420

Sent from my SM-N960U using Tapatalk

When the flanges are that bad a little Permatex 81878 works great.

I use a product called acousti seal. It's a vulcanizing goo (technical term haha) that has a lot of good applications. I will probbaly throw some on there just to protect it from water and salt intrusion. Cheers

Yea Mine has a big leak and I can see the exhaust smoke from both sections here and I think I’m beyond the point of put a gasket and call it a day. Might need to buy a whole new exhaust? Anything else I should check? Do while I’m down here?

BigMike

Those flanges are definitely in rough shape. But I don't see any reason not to try a gasket and some acousti seal first. It looks like someone has already been in there as they have through bolts instead of studs. If you have access to a torch I would heat those up and get it apart and asses it then. If it doesn't seal completely you're no worse off then you are now. The gaskets were only $3 each. The other thing you can do if you have access to a grinding wheel (I sometimes just use a cut off wheel on its side because its so thin you can get it in a lot of tight spots) you can grind down the ears (part the bolt goes through) so that the flange is flat all the way across. That way when you tighten it down the ears don't bottom out first before the gasket has a chance to squish and seal up. Just be careful not to mangle the inner pipe that protrudes past the flange.

There are a couple of shade tree ways to get past the bad flanges too but let's not get too carried away yet.

As far as what else to look for... I would look the frame over for soft spots. You can use a small hammer to tap away on spots that look suspect. Looks like you might have some fluid leaks going on as well. Doesn't hurt to try to figure out where that is coming from while you're under there. Cheers,

So far so good. I have put way more miles under more driving conditions than it ever went between CEL status before. Monitors are all showing OK on the scan tool. So I am very optimistic at this point. Now I can put my money into getting rid of X-REAS and upgrading to Bilsteins.

Mine leaked there too and the flanges looked like some of these pics. I replaced the gasket but it only lasted a few months. I then bought new flange pieces and welded them on plus went with a more solid gasket. Been quiet so far (since September) but wonder if the driver's side is now leaking as I get a p0430 about once a month.

That sucks, New England roads are tough on cars. I see you're in NH I'm in Maine. I go to NH often to hike. Not happy the mountains are getting ice and rain this weekend. This winter has been lame for winter hikes.

Thanks for the info!

I already replaced one CAT 3 years ago (PO430) and now im wondering if it was the just the gasket? I also got a PO420 a couple times in the past 3 months so I will have to check/replace the gasket before I buy another California CAT.

Thanks for this! I will have to give it a shot. I am dealing with an intermittent P0430 (comes on, clear the codes, it goes away for a month, then comes back).