P0420 Code

My CEL just came on in my 96 Taco 2.4L. According to Advanced Auto, it is the P0420 - Catalyst Efficiency below threshold bank 1. What the heck does that mean? From what I gather, it could be an exhaust manifold leak. The whole pipe up to the manifold, and the catalytic converter are new. The converter was stolen off it at the dealer lot, and he had them replaced. I fixed some pin holes a few weeks ago on some of the welds, but I didn't see anything major. I do hear a hissing sound under the hood when it is running, but I thought that it was the intake/throttle body. I'm going to see if I can find any cracks in the exhaust manifold. Any other ideas?

 

what brand is the converter you put back on there.. evidently it has higher flow rates then the ECU has parameters for witch leads to a cel light... the down stream o2 sees different then what the up-stream does,so the ECU thanks the converter is shot

 

I removed the manifold heat shield and:



I guess I'll be making a trip to an exhaust shop. Can it be fixed? or should I have it replaced?

I don't know about the converter. It just has numbers/letters stamped on the bottom.

 

i have seen headers Farley cheap for that model on sites.. and yeah it can be fixed takes a little talent to weld cast tho

 

look on ebay $60
http://cgi.ebay.com/ebaymotors/1996...003QQitemZ130233545388QQrdZ1QQsspagenameZWD1V

 

Ok, so I replaced the manifold. When I have a buddy put his hand over the tail pipe so I can check for leaks I hear two things. First, there is a leak where the manifold bolts to the exhaust pipe. One of the donut gaskets may be off, or maybe we didn't tighten it enough. I'll check that next. Also, the rear end of the muffler leaks very badly when we do this. It is coming out around where the pipe leaves the back of the muffler. It is not a welded joint, but looks like the pipe is stuck into the muffler. Is that normal? The muffler is fairly new.

 

yeah,thats odd.. put the welder on it!!!! weld every hole,crack,anything that leaks or a hole new exhaust system-hope not thats pricey

 

I had the muffler sealed up today. It only cost me 10 bucks! I also changed the fuel filter (that was fun), filled the tires, put in synthetic Mobile 1, changed the spark plugs and air filter. Now we'll see what kind of mileage I get. I was getting about 20mpg. I'd like to see if i can get any more than that.

 

thats great,hope everything works,those fuel filters BLOW---so hard to get to!!!!!! the 05s don't have one