gas mileage is horrible. I am gonna vag my 02 sensor...what are normal levels?

At wot you should see around .75-.85 depending on mods.

For years before 2001 you want to see around .86
 

anything higher is richer and lower is leaner. On the 2001 it reads more like a wide band, which means the readings get lower you get richer and higher are leaner. But both still want to be around .85-.86 which is right around 12.5:1

Check your fuel trims....
 

see if it's adding or subtracting any fuel.

Otherwise, during normal driving, it usually bounces between 0.2V to 0.7V

Also check for exhaust leaks, they can throw the sensor off

Bad EGT sensor can also affect gas mileage.

You mean Oxygen sensors? EGT just reads exhaust gas temp...
 

It has not effect on gas mileage.

Mau

No, I mean EGT sensor.
 

I had a bad EGT sensor and it did affect my gas mileage quite a bit. I averaged ~18-19 mpg with the faulty EGT sensor and 21+ mpg once it was replaced.

The EGT sensor DEFINITELY does affect gas mileage.

-Dave Pramanik

check the engine temp sensor too.

he means coolant temp sensor... it can influence how rich your car runs...
 

the engine uses it to control "cold start" fuel trims...

I don't think A4s have one...
 

at least the older ones don't