Hate to bump a old thread but I came across something very interesting recently. So my findings were the following the flex fuel sensor the one I tested at least from continental  technically only checks conductivity of the fuel adding water to the fuel will fool the sensor in to thinking it has more ethanol than is actually has. I have tested this on the bench with regular water and got a reading of E100 when it was just water. So unless you buying your e85 in  drums always make sure to take a sample and watch is separate.

Please do and report with findings. I would assume when buying e85 at the pump with tank below ground especially in the summer your gonna have more moisture in the fuel so technically I feel like it will be off more in the warm weather months rather than cold, but then again it depends on how much moisture is in the fuel tank below ground to begin with. I am curious if anyone else comes up with the same results. Also what flexfuel sensors are you guys using??

Precisely, old news. As for the sensor, effectively there is only one that is useful / reliable enough, the one from GM. (It is actually more than just a sensor, I think it has some meaningful circuitry in there).