First of all I have a 2002 A4 1.8T and its Emissions time. I was getting 2 codes P0411 and P0420. I replaced a vaccum hose for the combi valve and cleared the check engine light. It was off for two days and only 1 more monitor was incomplete. it was the catalyst monitor. the next morning while driving the darn light came back on and when i scanned it same P0420 code but now the catalyst monitor was ready. no P0411 so the vaccum hose did the trick.

My question now is. is it the catalyic converter itself or could it be an o2 sensor even tho the o2 monitor was ready before the light came back on. it seem like the catalyst monitor made the light come back when it changed to ready status. But no way to be sure what i need to fix and Dealer wants $700 for the cat and $100 core charge. what if i change cat and it is just the o2 sensor... i dont know what to do. ANY SUGGESTIONS?!?!?

 

whenever i have a car come into my shop with a po420 i replace the the catalytic converter. i havent been in a situation where that didnt fix the problem. i havent had an audi with that problem yet but, for the most part i think that would fix your problem.

 

well does it have to be the $700 cat from the dealer or are there other brands that will still pass emissions on audi?

 

if you want a direct fit then you will have to pay the ca$h. although, if you want to cut and weld you can get a universal for around $100

 

You got 3 choices i guess:
OEM CAT
TestPipe (150) + Chip 1+ (500) + injectors every stage 1+ or stage 2 (Revo) flash will erase CEL caused by the testpipe
HIGHFLOW CAT -it is 350 from 034motorsports... Contact them for more info for your situation http://www.audizine.com/forum/showthread.php?t=233433

 

Will it pass emissions if i get the test pipe and chip upgrade... And the chip upgrade will cancel the code for not having a cat right?

 

Where u from? Depending what kind of an emissions test you got in your state. Some state just checl for the faults codes, some for the codes + exhaust smoke.
If your doesnt require smoke test- they yes, with a chip you should be fine casue you wont have any Check engine lights.

 

im from Bridgeport CT. not sure if they check for smoke or if they look under the car anymore to see if there is a cat? But i would rather pay around $700 for test pipe and chip then a stock cat for around same price.. .at least i can upgrade a little

 

^^^ If they dont have a smoke test, then it takes 5 min only for the emission test.
You can always buy a high flow cat, it works basically like a testpipe, but u wont have a cel even when u are stock. Contact those guys for more info.

 

but will the HI Flow Cat fit the stock exhaust or will i need to get a new exhaust cause it says 3"