Catalytic Converter Question Code P0420

[jmspain]

Hello,

I'm new to the forum, but before signing up, I read through numerous questions about the 420 trying to find answers. I apologize if this thread duplicates any prior thread. I'm just looking for help.

My 2002 Passat 1.8T is throwing the 420- code, and I need to pass emissions within the next two weeks. I believe that I can put the cat on myself, but I want to make sure that the Cat is the problem, and that I buy the right replacement for it.
I have spoken with a number of mechanics, and the consensus opinion is that the cat needs to be replaced. The dealership wants $1300, and I've gotten two more quotes at about $900, and one at $648. At those prices, I'd rather buy one and do it myself. I've seen a couple of links here on the forum to specific cats, but I'm hesitant to buy one without knowing for sure it's the one I need. Or if I need it at all. Which one of these two is the best? Are these "aftermarket"?

2001-2005 VW Passat Catalytic Converter for L4 1.8L Turbo (engine ID AWM) at 1AAuto.com

1998-2005 Volkswagen Passat Catalytic Converter - Exhaust - Bosal 98-05 Passat Catalytic Converter - 7436-05017903 - PartsGeek


I should mention that the "coolant inlet" was recently replaced, and I've wondered if the mechanic who did that could have left a vacuum line loose that might be causing the code.

I also wonder if unplugging the negative battery cable might clear it as well (long enough for me to get it through emissions).

Getting it off the ground could be an issue, I know. But for a lot less than $648 I could buy a cat and ramps and a decent floor jack.

What's the difference between direct fit and oem or are the two synonymous?

Please help.

Thanks in advance,
Jack

[NUISANCE]

What do you mean coolant inlet? On the back of the head? If so, the plugs for both sensors are behind the intake manifold. Maybe he unplugged them for room but didn't plug them back in.

[ylwagon]

I don't have any advice to offer as to which one to get, sorry, but I'll tell you that life will be easier if you invest in some tools that you may not have: long 3/8" extensions for your ratchet, and a 13mm U-joint socket. You'll also need a 22mm wrench for the O2 sensors. With jack-stands to hold the car up, you disconnect the exhaust coupling clamp about mid-way under car. The challenge is to get all three nuts off the turbo's studs, and one has to be done with the extensions and your U-joint 13mm socket from under the car, from what I remember.

Where in the Atlanta area are you? I was in Alpharetta amoung other cities last month.

[jmspain]

@nuisance - I'll definitely check both oxygen sensors, thanks.

@ylwagon I live about 10 miles south of Alpharetta actually in midtown Atlanta. Thanks for the tip. I'm not sure if I know what a U-joint socket is, but I'll definitely ask at the parts store.

Thank you both.

[scotts13]

Those are both aftermarket converters, as in "not supplied by VWOA". For U-joint read "universal joint"; it has a swivel at the base so it will angle a bit to get around obstructions.

[NUISANCE]

If you are going to change the cat I am going to make your life a whole lot easier-

Unbolt the cat from the turbo, get under the car and remove the slip joint connecting the down pipe and exhaust. Now pull the down pipe out with the cat attached, it will fit with some love as i have done it. Pop off the old cat, put on new one and reinstall. All in all, maybe an hr worth of work.

Also, is there a visual check under the hood along with an emmisions test where you are? If there is no visual check just an emission test you will past with a test pipe. I passed the sniffer test here in cali with a test pipe.......