So, I just put a new engine in the Frontier back in October. The check engine light came on after the hard reset and fuel trim adjustments.

I pull the diag computer out and check the codes. 420/430. GODDAMMIT!!!!! The converters are bad!!!! I failed to even look in them when I yanked the engine. I tried every cheat workaround in the book. From offsets to resistor/cap combos. Nope. THe elements seemed just too degraded and then winter hit. No working on the truck until warmer weather.

Well today I yanked the first manifold and found this.

One of these things is not like the other........

This message has been edited. Last edited by: Mars_Attacks, March 01, 2025 03:44 PM

That top one will have blown chunks into whatever is the next restriction in the system, be it a resonator, muffler, or even a sub-catalyst (not monitored by the ECM). They did well to last as long as they did. Are they integrated with the exhaust manifolds?

The resonator is clean. I bet the powder is in the muffler.

One of the last jobs I did for a client was the same problem on a Hyundai Accident Accent. It had such severe back pressure that it would barely even move. The chunks had lodged in the sub-cat, but I was able to get it off and clean it out, and it stopped the debris from going any further. It was otherwise undamaged.

I got a SECOND one to do on this and it's BURIED.

This was the easy one. The other is under the intake and by the steering and has the EGR bung in it.

How picky is the computer? I replaced the factory cat with an aftermarket high flow one a 2002 Grand Cherokee when I put on a performance muffler and it didn’t trigger any codes- also upped the V8’s performance a bit.

Well, the guts are missing from the old cat.

The computer noticed.

Well that's no fun!

Congrats on being able to show us two cats with intact studs and clean bolt holes.

I had to buy four cats last year as the previous owner had straight piped the exhaust and left all four of the O2 sensors hanging by the harness.

Decided that since it had no mufflers or tips, no aftermarket exhaust was available either, I had to make my own.

Realized that since I was over budget just a little, long tube headers and exhaust cut-outs would put me over budget for sure.

Top os old, bottom is new.

I can't wait to pull the driver side.

Oh joy.

I just dealt with this on my Volvo. The local shop used something to clean the catalytic converters out. Way cheaper than replacing. Seems to be working ok now. No more P0420 code.

quote:

Originally posted by james_1234:
I just dealt with this on my Volvo. The local shop used something to clean the catalytic converters out. Way cheaper than replacing. Seems to be working ok now. No more P0420 code.

There's no cleaning this...the catalyst is gone, lol!

At least the OP is in Georgia....up here all those studs would have been rusted to hell and snapped off, so you'd either being trying to drill/knock them out from under the car, or pull the manifolds, at which point those studs would snap off in the heads, and so on and so forth. I hate working on exhaust.

Another plus is the engine is fresh and all the fasteners were still easy to remove.

This would have been light years easier if I had listened to my own advice and replaced them with the engine out.

I didn't even check the catalyst when I pulled the engine. The new engine had no converters.

I’m fixing to have to replace everything from the exhaust manifolds to the tailpipe on my 4Runner, not looking forward to it. I keep getting intermittent codes for the cats. I used a bottle of “Cat Clean” in the gas tank.. seemed to help for awhile but the check engine light just came back on. I’m going to go the route with aftermarket headers from Doug Thorley and Magnaflow for the exhaust.

I have a little mechanical and engine knowledge...but...is that just a simple screen filter to prevent debris from going into the exhaust system?

^^^ No. It is the actual catalytic element. It can't be a solid block or the exhaust wouldn't be able to go through it. The empty one in the OP had this break up and go downstream.

Here's the other side.

It's Fukkedashima'd.

Daaang, how many miles are on those cats? Odd way to ask their age, I guess.

400,000 miles.

I’m interested…and as mentioned, moderately mechanically inclined…but is that a typical 400K appearance? Should it never have made it to 400K? Is this a “never think about it for the life of the vehicle” part?