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New Catalytic Converter

48K views 9 replies 8 participants last post by  313hitman 
#1 ·
So Ive been driving around with this horrible check engine light on, with a code of P0421( warm-up catalyst on bank one below threshold)and time for inspection is coming up so I decided to get it fixed. I took it to a shop and they told me it was my cat, the cars over 100K so Mazda wont do it. Ive asked a few people and everyone said im going to need a universal cat b/c no one makes a direct fit for the 6. I came across this magnaflow and was making sure if it would fit or not. http://www.amazon.com/gp/product/compatibi...=UTF8&i=225
http://www.car-sound.com/02product/display...universal=53004
It says "FRONT" for the 2003-2005 V6 Mazda, is there any other cat in this car?
 
#2 ·
So Ive been driving around with this horrible check engine light on, with a code of P0421( warm-up catalyst on bank one below threshold)and time for inspection is coming up so I decided to get it fixed. I took it to a shop and they told me it was my cat, the cars over 100K so Mazda wont do it. Ive asked a few people and everyone said im going to need a universal cat b/c no one makes a direct fit for the 6. I came across this magnaflow and was making sure if it would fit or not. http://www.amazon.com/gp/product/compatibi...=UTF8&i=225
http://www.car-sound.com/02product/display...universal=53004
It says "FRONT" for the 2003-2005 V6 Mazda, is there any other cat in this car?[/b]
If it's specifically for your car, yes it will fit.

Amazon lists this as a "universal", which means maybe yes, maybe no. After all, they list 540 "fitments" for this same part number, so its pretty obvious it's not an exact fit for anything in particular.

They provide no measurments other than pipe diameter, so it's nearly impossible to say if it will fit under your car or not. If not it could require a lot of costly exhaust system fabricating to make it fit, and many state's emission laws require an exact replacement, which could mean your car would fail a visual inspection if one is done. Someone has to make an exact fit replacement, even if only Mazda.

While it might cost a bit more, your best bet is a cat made for your car, not a "universal". Are you sure you have a failed cat or something else that's giving you the CEL code? What you've listed does indeed sound like a cat but could also be a failed post-cat O2 sensor.


EDIT:
Well, I had to dig out the service manual for something else, so while I was there.............it appears the V6 cars have THREE catalytic converters. One "warm-up" cat in each exhaust manifold, and a single one in the exhaust pipe just before the flange connecting it to the rear of the system.

And you did mention the V6, so I assume you car is a V6. If so, P0421 refers to the Warm-up Catalyst on the right bank (the one toward the rear of the engine compartment. These "warm-up" cats are actually part of the exhaust manifold, so to replace it means you're most likely only going to find the part from Mazda or if you're lucky enough, a good used one from a salvage yard.
This assumes it is indeed the cat that has failed. It's possible that it could be a bad post-cat O2 sensor.

If you car is the I-4, they also have a "warm-up" cat in the exhaust manifold and one in the exhaust pipe. Obvious difference is that the I-4 only has one exhaust manifold, and therefore only one "warm-up" cat.

Either way, I'm sure it's an expensive part from Mazda and seeing how it's made rather doubtful there's an aftermarket replacement for it.

I'd check the O2 sensor first, they're not too expensive to replace if that's the problem. If it is indeed the cat and you have no luck at salvage yards, you might contact Tiffany at Showcase Mazda to see what kind of price she can give you on a new one. They're a forum sponsor on this board.
 
#3 ·
So Ive been driving around with this horrible check engine light on, with a code of P0421( warm-up catalyst on bank one below threshold)and time for inspection is coming up so I decided to get it fixed. I took it to a shop and they told me it was my cat, the cars over 100K so Mazda wont do it. Ive asked a few people and everyone said im going to need a universal cat b/c no one makes a direct fit for the 6. I came across this magnaflow and was making sure if it would fit or not. http://www.amazon.com/gp/product/compatibi...=UTF8&i=225
http://www.car-sound.com/02product/display...universal=53004
It says "FRONT" for the 2003-2005 V6 Mazda, is there any other cat in this car?[/b]
Yes, our car has a "pre-cat" in the engine bay. Not sure if that's what the "front" refers to.

From RPM website: One of the biggest power restrictions on the Mazda 6s is the factory exhaust system. The entire factory exhaust system is a huge source of backpressure. Both front and rear exhaust manifolds are very restrictive due to their hydro-formed construction, shape and size. In addition, both manifolds contain a pre-cat, which is a catalytic converter before the main catalytic converter.
 
#5 ·
So this could as well be the 02 sensor? if so which one would it be? before cat or after? And is there any way to check if the o2 sensors are working as they should be? (is it expensive?)[/b]
It would be the sensor after the cat..

I really dont know what they cost for the Mazda6, I purchased one for a 2001 Impala a couple years ago and it was around $80.
 
#6 ·
There are FOUR cats on your car. The two pre-cats are located on the headers themselves. Neither one of those part numbers you looked up will fit where the pre-cat is. Here's a picture:

[attachment=30687:6sexhaust.gif]

Pre-cats: #12 and #13
Bank one is the rear bank, so the cat in question (according to your code) is #12

If you wanna check the O2 sensors check #7

p.s. The regular cats are: #5 and #3
 

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#7 ·
Hopefully its just the sensor which would cost you a little over $200 for part plus install. If the actual cat went bad and needs replacing... Ugh we can all thanks Mazda for the nasty cost of actually swapping out the header. If thats the route you have to go aftermarket..
 
#8 ·
Everyone - I know this is an old discussion, but I am having a similar problem (P0421 error) on my 2003 Mazda 6S 3.0L. The dealership is saying I need a new "3-way Warm-up Catalytic Converter" and that the part number is AJ57-2055XC.

When I check online, they are saying this part number is for a rear exhaust manifold. Is the cat a built-in component? Did they give me the wrong part number? From what I understand this vehicle has 4 cats and I just want to make sure I get the right one replaced. If you can't tell, I'm obviously looking for someone other than the dealership to perform these repairs. Too costly$$$$
 
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