xr4tic

Is this normal? The primary O2 reads around 0.850V, and the secondary is reading 0.910V, which is showing the exhaust as being a lot richer after the cat than before.

I would think the second O2 sensor would read the same or less than the primary sensor.

And the readings are the same with and without the water injection enabled.

The cat has 80K miles on it, 55K of those are chipped miles.

Can someone check and see if you get the same readings? I think it's group 31 (it's 30-something) in VAG-COM.

Thanks,

scott12v@pghaudi

I won't be any help answering the question you asked, but I have a question for you...

What are you using to measure the sensor? I have a A/F meter hooked up, but would like to get the actual values rather than seeing a light.

Thanks,
Scott

Audiboy

OBDII tool (PC based preferrably)

Ferris TMK

Remeber you're measuring O2 content not unburned fuel. So when you measure the first reading there is some O2 in the exhaust, it hits the cats w/ fuel and the fuel gets burned using some of the left over O2. Then the post cat O2 sensor will read less O2, since you burned some. The only other thing it could be is bad O2 sensor, but all in all it sounds normal..

xr4tic

I use a VAG-COM. Good for datalogging too.

scott12v@pghaudi

I guess its time to move beyond simply resetting the inspection notice and airbag light!

Thanks,
Scott

Kevin K2

for the rich end, o2 output will be as much as .1V higher if exh temps are cooler, for same a/f ratio.

mabe some clogging of old cat.