Pour in the highest octane, non-ethanol fuel you can get and see if the readout changes.
If it's dead bang on 11% then I would question the sensor. Another quick test, just take it out and run normal (in an american accent) gas-o-line through it and see if the sampled ethanol or lack of changes.
United E85 here in the land of drop bears does vary a bit, I've had as high as E87 (could be water in their tanks too, who knows)