Need help with Cat Converter

Im sure I need to replace my catalytic converter. I went to a mechanic this morning and he said it may only be a vaccum leak some where causing me to get a P420 code.

But, if I were to replace the catalytic converter I saw that theres a bunch of different fits. I found this one on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=190283171790

My 8th digit on my VIN # is a U. But it also says in the item info that its for a AX4N Automatic Transmission, Transmission code "X". How do I know if this will fit my car and how do I find my transmission code?

Just to be sure, you should contact your dealer's service department to see if your converter is warrantied as the Feds pushed hard on these things to work all the time.

Probably Rod knows this, but I think the trans is identified on the vehicle certification label and the trans id label. On the vcl, it's the last item on the far right listed in a series of paint, trim, etc. The bottom pan on the trans will say if it's an X, etc., but you may more detail than that, so you will have to find the trans id tag which I believe is on top of the trans bell housing. Someone else will have to say where it specifically is if I'm wrong.

What makes you think your cat is bad besides the one code? Does it make any noise like a loud sucking or blowing sound? Does the exhaust sound plugged? Does your engine lack power? Replacing the cat is no fun job. Replacing the cat from joint to joint is the best method, though won't necessarily seem that easy, but it sure beats trying to splice one in a very tight spot. Been there. Expensive was a motivator for me as it only comes as a Y pipe with two cats. That too looked to be a real pita!.

BTW, it would greatly help us to help you if you can tell us the year and engine and anything else that would be relevant. I assume the U code is for the 3.0 engine.

I don't believe there is any entry in the VIN that identifies the transmission. Often they are identified based on the shape of the tranny pan and number of bolts. You might try one of the online auto parts stores, try to order a transmission filter and gasket kit and see if it offers any insight.

As for the engine code, yeah, the 8th VIN identifies the engine, and I believe that's pretty standard regardless of manufacturer.

I do suspect that catalytic converters get condemned too often by the parts stores when they see a "catalyst efficiency" code. If the car runs and drives well, I'd suggest you try replacing the oxygen sensor after the Bank 2 converter. If that fixes it, you can expect that the other 3 won't be too far behind and may want to plan to replace them all soon. Chance are your fuel economy will increase enough to shortly offset the cost of the sensors if you can replace them yourself, avoiding the professional labor cost.

Depending on the age and mileage of your car, if you find you need a new converter, you will want to figure out what caused the converter to fail. You might have a misfire or other issue that caused a rich condition and caused the converter to overheat.

-Rod

The cats all bolt up pretty much the same as long as both cars are OHV or both OHV.

Well I did the head gaskets over in the car because they were leaking. I'm figuring that some antifreeze may have gone through the converter. Also when I had the engine all put back together my friend had put two spark plugs on backwards and one of the pipes going to the converter were actually glowing red.

I did change an O2 sensor. My father has a friend whos a mechanic and he lets me use his lift on a Saturday if its not to busy. He gave me a universal O2 sensor and showed me which sensor that was supposed to be giving me the error code. So I changed that one out but no luck. I had told him about the glowing and gasket job and what not and he said it was probably because antifreeze is oil based and ruined the converter or most likely because I had the pipe glowing..

But the car lacks no power, exhaust doesnt smell at all. You'de honestly never be able to tell that theres something wrong with it if the engine light wasnt on. It has no typical symptoms for a bad converter at all.

Does you father's friend happen to have a scan tool with a datastream mode? If so, you could monitor the bank 2 sensor 1 versus the bank 2 sensor 2 and see if they indicate the converter is working properly or not. You should have a lot of switching on sensor 1 and very little switching on sensor 2. If sensors 1 and 2 switch (cross 0.45 V) rapidly, then the converter is not doing its job or sensor 2 is not responding appropriately.

-Rod