AudiAgFan

I have a custom 3" turbo back no cat exaust on it and getting the following codes

DTC (codes)
P0422- Main Catalyst Below Thershold (Bank1)
DTC Pending (codes)
P0327- Knock Sensor 1 Circuit Low Input Bank 1 or 1 Sensor.

It smells way too rich, i think the first 02 sensor is bad, i also thinking about putting a 3" cat late on.

So here are my questions, ecs has 2 O2 sensors a $30 and $90, what is the difference?
What else can i do to make the car run better (lean)?
what about this knock sensor? i use 92 non-oxy.

Thanks
sam
98.5 a4 1.8tqm

JAFO

because you have no cat. if this isn't a track only car join the human race and put the cat back on.

AudiAgFan

and i dind't like it i'll put a 3" cat on it, but bank 1 isn't that before the cat or is that bank 0?

JAFO

only the 2,8 has a bank 2. S1B1 is in front of the cat S2B1 is behind the cat.

AudiAgFan

one before the cat(black connector) one after the car(brown)

JAFO

sensor 1 bank 1 is before the cat. sensor 2 bank 1 is behind the cat. 2.8's have 4 sensors 2 for each bank.