I am working on getting a flex fuel tune done for the truck but i had some basic questions. Where is the sensor located and does anybody know if it works like GMs virtual sensor or reads actual content?

 

https://www.autoserviceworld.com/car...x-fuel-faults/ I don't know anything about the modern world but just always assumed they used 02 sensors to tell ecm what it was running on. I thought it was an interesting read. Going to need 2 kinds of mechanics in the future, 1 guy is nuts and bolts and the other will go nuts.