2004 s40 5cyl catalytic converter replacement
 

Does anyone know where I can get a cat converter for my 2004 s40 2.4l 5cyl (not turbo)? I was told it's a dealer only part and I cant afford $1200 for just the converter right now.

plenty of online parts stores -

FCP Euro, EEuroparts, IPD USA, Rock Auto, AZ Autohaus are a few that I've used. Also Tasca Parts is a good source for dealer parts. Just curious why you think you need a new cat converter (the cat efficiency fault code is often caused by an intake air leak, exhaust leak or a weak O2 sensor..)

I was told the code that comes up for the check engine light that is on is for a cat converter that needs replacing. The estimates I've gotten are crazy expensive so I am getting a second and if necessary a third opinion.

have the shop (or Autozone etc) scan for the check engine light fault codes and ask for a print out to see if there's more than one code. The typical cat converter fault code is a P0420 which is saying the front oxygen sensor and rear oxygen sensors signals are not correlating - which means either one of the sensors is off or the converter is not working efficiently and sometimes the sensors are off due to an unrelated problem (which may have additional codes).

fully equipped shops can scan for the fault codes, the fuel mix and even check the temperature of the converter (ie via a heat detector) and measure the values of the oxygen sensors before recommending replacing the converter. First step is to get a print out of the codes then start googling (you can read up on the P0420 code to see what I mean).

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I recently recommended again to two people with CAT problems and both were successful getting their smog done in CA. LA is even stricter then NorCal if I remember correctly. In CA if you want to run clean and avoid CAT and other potential emission problems you need to run either Chevron or Costco's highest grade and Rotella T6 5W-40 motor oil. .
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After changing over to the above use 2 Chevron Techron Cleaner on a full tank of gas till you can utilize the method in the below video. My cousin in CA is attempting this now on the 2000 Sienna I helped him purchase years ago at 154K and now has 199K. If Robert Spinner is on this forum he was one of those who successfully done this. I was not the one who recommended this to him however.
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really depends on why the OP suspects a new cat is needed and did they check for intake air leaks or exhaust leaks, a bad rear o2 sensor etc. Did the car fail emissions or is it throwing a CEL code (which will fail emissions). Useful to know what CEL code (ie a P0420?) has been set. Not sure about the correlation of specific brands of motor oil to a failed cat. This treatment is suggesting running detergents which will help remove deposits - presumably unburnt HCs - to allow the cat to run more efficiently. You can get the same detergent by running brand name premium gas for a few tankfuls as well (although it can't hurt to drop in Techron every so often - I do it with every oil change and run 93 premium every 3 or 4 tankfuls). Point here is this won't fix an engine that is consuming oil and there's plenty of test articles disputing the effectiveness of using additives to clean a cat once its starting to fail. While it can't really hurt, there should be reasonable expectations that it won't help, particularly in an older engine that's consuming oil.