UEGO Sensor condition
 

Is there any way to determine if a UEGO sense (controlled by an AEM controller) is reading too high, or too low? I feel like my 14.7 is not truly 14.7AFR, and that my car is running richer than it should.
My tune is pretty spot on, but I still can't get past like 18 MPG highway. I go to school about 40 miles away from home, and using ~4 gallons for a roundtrip shouldn't be happening.
Albeit I'm in boost sometimes, but most of the time I'm cruising in vacuum going around the speed limit on the highway.
My WBO2 sensor was exposed to some pretty violent flames because my ignition was 180* off (engine wouldn't start, but loud banging did occur. Base tune for my ECU had the pins reversed for ignition). Thoughts?

nope. they calibrate it once before packaging it -- if it degrades there's really no way of knowing unless you use something else to reference.

what are your cruise AFRs and spark advance?

put in another one and check.

most the time people get bad mileage is because of several different things in the tune, not just the cruise afr's and such.

AFRs are between Mid 14s to Mid 15s. Timing is low 30s to high 30s.

Tune attached...can't attach the RusEFI ini for whatever reason. http://rusefi.com/build_server/rusefi_bundle.zip

It is just a Bosch LSU 4.2 sensor. Google it, a new one is around $80. I killed one a few years ago from running leaded aviation fuel, 100LL.