Hello. I have a 98 a4q 2.8 30v, it has 180k. I got a cel and it is the p0432. If I clear it it comes back in a couple hundred miles. Does anyone have experience with the Magnaflow or Monster Flo? Can I just gut it? Will the cel stay off? I live in PA and we have emissions testing. I worked at a VW shop in the late 80's and I remember the boss putting a gti up on the lift and running it hard while slamming the cat with a hammer. The ceramic was all over the floor.
Which side of the car is bank 2?
How does the 02 sensor pick-up (if it does) the cat problem if it is upstream?
I read the audiforums archives but still have questions.
Any information would be helpful. Thanks.

 

no you can't gut it.

you can go aftermarket, but they have to be Audi specs replacements. i've had to replace new aftermarket cats cause they MIL keeps coming back on.

bank 2 is the left side if your sitting in the car.

and you have two o2 sensors per bank. they compare readings. the second o2 has to read lower but a certain amount or the Cat Efficiency code is set

 

I only see one 02 sensor on each side in front of the cats? Schematic from Bentley a4 manual. Thanks.

 

G39, G108, G131, and G130

4 oxygen sensors.

 

Sorry, I'm slow. Thanks for response.

I see G130 and G131 are the 02 sensors before the cats, one on each side. There must be two behind the cats that aren't shown. I see in the fuel / ign. section that there are two sensors per bank. thanks.

 

ya there is sensors up the wazoo on these cars its hard to to a custom exaust on them without realllllly knowin what your doin.