2015 Sierra FHO RPO CODE but has flex fuel sensor

Supermofool · February 4, 2021

My 2015 GMC Sierra has the RPO Code of FH0 that states it’s non flex fuel. I looked under it today and it has the flex fuel sensor already plumbed in and connected. Seems odd to me. I did all the research on here to get all the parts i needed but i guess i won’t be needing to do any of that. Maybe buy an HP tuner and check if the sensor is active. I was wondering if anyone has come across this on their truck?

CamGTP · February 4, 2021

I suppose it's very possible that it's just there but not active in the calibration. 2014's where pretty much the only year that it was a factory thing, maybe your truck is an early 2015 model.

If you had a nice scan tool that can read alcohol percent that would be the best way to figure that out. If it's reading 14.1 all the time for stoich and the alcohol content is stuck around 9-10% it may not be active. A quick test would be to put a gallon or two of E85 in the tank when it's at about 1/4 tank, see if the reading goes up.