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Discussion Starter #1
OK so I own a small car lot and sell Nissan Frontier trucks. This morning I discovered that some nice person came in at night and sawed off five of the convertors off my frontiers. 4 of them are 2000, 1 is a 2004, they are all 2.4Liter motors.

My question is where and what kind of convertor should I purchase to replace these? I need CHEAP replacements that will work with OBD2 technology and pass the emission test we have here in Austin Texas.
 

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Are They Primary Cats Or Secondary?
 

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I Understand But A Primary Cat Is Pretty High Up And Not Really Accessable On Many Vehicle. While I Dont Have A 1gen 2nd Gens Have 4 Cats(so Do Jaguar And Many Others) The Secondary Cats Are Alot Easier For Theives To Cut Especially On Trucks. So Evan A 4 Banger Can Have 2 Cats, Primary And Secondary, Or Up And Down Stream. But The Secondaries Are Not Monitored For Obdii Emmissions By The 02 Sensors. And Unless An Inspector Looks You Couldnt Tell From The State Machine....so Back To My Original Question Upstream Or Down(if There Is Both And Maybe A 1st Gen Owner Will Chime In)
 

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as far as i can recall, my 2004 only has 1 cat.... but ill look it up in my FSM. any aftermarket cat will suffice... i would contact a muffler shop in your area to see what they have in stock.
 

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Discussion Starter #7 (Edited)
It is the secondary on all of them. The 200 models are an easy fix because they are not monitored by the o2 sensors. But, I believe the 2004 model has an o2 sensor after the secondary CAT and will require a more expensive CAT. What are you thoughts on this?

OK, I looked in detail under all of these trucks and the 2000 models have a o2 sensor after the secondary CAT and the 2004 has the o2 sensor before the secondary CAT. I called a few muffler shops and they stated that the 2000 models do not monitor the secondary CAT and that I can get by with a cheap replacement. But if the o2 sensors are after the CAT on the 2000 models and the 2004 model has it before the CAT wouldn't that mean that the 2000 models are monitered? and the 2004 model is not?

HELP?
 

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Not necessarily an issue. The readings of the second sensor might be a lot more "relaxed" than we get the impression of knowing. You see the sensor after it and think to yourself it makes a big deal, but it could be just monitoring to make sure that the AF ration is correct, leaning or richening the fuel supply. Probably the best bet is to take one in, get the cheapo installed and then get it inspected. I think technically since your are making "modifications" to he exhaust system, it is required to be retested to make sure it is up to snuff, and a lot of muffler shops will test it after a cat install to make sure they are on target. If not, get it in writing that they will work with you and allow you to go get it checked out. An inspection shop should let you throw them a couple bucks their way to hook up the exhaust meter and check it out for you.
 

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It is the secondary on all of them. The 200 models are an easy fix because they are not monitored by the o2 sensors. But, I believe the 2004 model has an o2 sensor after the secondary CAT and will require a more expensive CAT. What are you thoughts on this?

OK, I looked in detail under all of these trucks and the 2000 models have a o2 sensor after the secondary CAT and the 2004 has the o2 sensor before the secondary CAT. I called a few muffler shops and they stated that the 2000 models do not monitor the secondary CAT and that I can get by with a cheap replacement. But if the o2 sensors are after the CAT on the 2000 models and the 2004 model has it before the CAT wouldn't that mean that the 2000 models are monitered? and the 2004 model is not?

HELP?
you have a choice of putting in straight pipe in place of secondaries. In Texas its only a visual check of emmissions equipment in place is done. Since 1996 and later are OBDII they are plugged into the state machine during the inspection process. If there are no codes, and you pass the visual insp youre fine. And cheap cat is just fine if you want to stay totally legal all around

Not necessarily an issue. The readings of the second sensor might be a lot more "relaxed" than we get the impression of knowing. You see the sensor after it and think to yourself it makes a big deal, but it could be just monitoring to make sure that the AF ration is correct, leaning or richening the fuel supply. Probably the best bet is to take one in, get the cheapo installed and then get it inspected. I think technically since your are making "modifications" to he exhaust system, it is required to be retested to make sure it is up to snuff, and a lot of muffler shops will test it after a cat install to make sure they are on target. If not, get it in writing that they will work with you and allow you to go get it checked out. An inspection shop should let you throw them a couple bucks their way to hook up the exhaust meter and check it out for you.
see my post above, for Texas state requirments(I am an inspector in Texas) Also upstream 02 sensor monitors air to fuel ratios, not downstream, downstream only monitor if the cats are doing their jobs efficiently. And we dont tailpipe sniff on OBDII at all anymore, if you no longer have factory ecu and inop OBDII port(performance builds etc) you fail the state, we can no longer sniff OBDII cars if port is damaged, missing or inop..it fails!!! We only sniff non OBDII cars only rolling dyno for emissions testing
 

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Roger that, good clarification. I haven't lived in Texas in over ten years, I was just going off of my Exxon gas station attendant days.
 
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