I don't know if someone answered this yet, but the sensors probably have a reference voltage coming out of the ECU and it might be shared. From my dealings with my bike if a sensor or something is screwy it seems to run super rich and mileage drops in the 20's. (when I had Map sensor problems)
First I would check the what the reference should be and what the reference voltage is at the sensor. If this is wrong I would disconnect the sensors then test it at the ECU.
If its right at the ECU, I would start looking into the wiring. Ktm's wiring is so ugly it wouldn't surprise me if you had a short or partial short somewhere.
2012 300 EC Race
2010 690 R
2007 990 S