Topic: Help with catalytic converter, 2RZ

[toyodaaddict]

I'm just finishing up a rebuild on the 2RZ in my Mom's 1995 Tacoma 2wd. I've got about 50 miles on it and I'm getting a P0420 code.  Anyone have any opinions on what to do about replacing the cat? Does Toyota work well with aftermarket or is it worth $800 for oem? I've never had to deal with a catalytic converter before.


The cat has 275K on it. I changed the o2 sensors (Denso) during the rebuild. A head gasket leak is what got me into the engine in the first place, so the cat has seen some coolant. Would you guys agree it's a pretty safe bet that the cat is the issue?

[Gnarly4X]

If the code is throwing a CAT, I'd go with a MagnaFlow OEM, way less expensive than Toyota.

MagnaFlow has solid historical reputation. 

By the way.... great job on rebuilding a 2RZ!! 

Gnarls.

[a1gemmel]

Personally I drive to Wyoming to buy EPA cats because CARB cats are an absolute scam, but that might not be an option for other folks

If the government is reading this, for legal reasons this is a joke.

[a1gemmel]

Also, you can usually visually inspect a cat - it'll either be clogged or have holes blown through the honeycomb if it's bad.

[sirdeuce]

Might not even be the cat. Try checking your connections FIRST! A little grease, oil, dirt or corrosion can cause a problem. Could be the O2 sensor heater or exhaust leak. Eliminate any possible issues before spending half the month's rent on an unecessary part.

Since it's a rebuild, try waiting until the engine is properly broken in before you get antsy about replacing components. Until the engine is broken in there are excessive oils and assembly lube going out the exhaust. After break-in take the thing on a good long road trip to ensure things clear out of the exhaust system.

As for going out of state for a cat, especially if you live in good 'ol Commiefornia, not a good idea. California requires a C.A.R.B. E.O. # stamped in the cat body. The Techs DO check, it's part of the proceedure they're required to perform.

[toyodaaddict [OP]]

Thanks for the helpful info guys. Sounds like an aftermarket cat (magnaflow) should be fine.

I didn't know that the only thing to go wrong with a cat was physical damage, so I will take a look inside.

I don't have to do emissions and can buy whatever cat I want, so no issue there.


The fact that the engine is a fresh rebuild has me extra worried about this. I'm worried that whatever is setting off the P0420 CEL could be causing an air/fuel issue. I just don't want to hurt the engine.  When I installed the new o2 sensors, some rusty metal came off with the gasket. When I put the new sensor/gasket on there was a little gap in the middle but when I tightened it down, it looked like it probably sealed but I'm not 100% sure. Any ideas how to test the exhaust for leaks? It would really suck to replace the cat and find out it was an exhaust leak. edit: google says air and soapy water for exhaust leak

Another thing I will add is the truck had this code before the rebuild and it came back after the rebuild. It's actually what led to me finding the blown head gasket.

[toyodaaddict [OP]]

To conclude this thread, I used a shop vac to blow air up the tail pipe. That and a little soapy water made it very easy to find that I had two leaks. A big one at the rear of the cat and a very small one at the rear oxygen sensor. I replaced the bad flange and the oxygen sensor mount and all is well. The cat looked fine inside. Engine now has 225 miles and no CEL.