# Flex Fuel Sensor (is this how it works?)

**URL:** <https://community.cartalk.com/t/flex-fuel-sensor-is-this-how-it-works/31229>\
**Category:** Maintenance/Repairs\
**Created:** [May 31, 2009, 2:52pm UTC](https://community.cartalk.com/t/flex-fuel-sensor-is-this-how-it-works/31229 "2009-05-31T14:52:05Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dodge\_racer16](https://avatars.discourse-cdn.com/v4/letter/d/cab0a1/32.png) [@dodge\_racer16](https://community.cartalk.com/u/dodge_racer16)\
**Post date:** [May 31, 2009, 2:52pm UTC](https://community.cartalk.com/t/flex-fuel-sensor-is-this-how-it-works/31229/1 "2009-05-31T14:52:05Z")

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The way I understand most of the research that I have done on this sensor, it has 2 different modes. It is either sending out a signal, or no signal at all. If the PCM is getting no signal, it will run off unleaded gasoline only, but if it sends out some sort of a signal it will run off ethanol. As I have said before, if I disconnect the harness from the sensor while the truck is running it has no change in idle and does not stall. So this tells me that if I keep this disconnected I should be fine to run the truck, because the sensor cant malfunction and send out the wrong signal. Does this sound logical?

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**Author:** ![87\_Ranger](https://avatars.discourse-cdn.com/v4/letter/8/f14d63/32.png) [@87\_Ranger](https://community.cartalk.com/u/87_Ranger)\
**Post date:** [May 31, 2009, 5:54pm UTC](https://community.cartalk.com/t/flex-fuel-sensor-is-this-how-it-works/31229/2 "2009-05-31T17:54:14Z")

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Did you look at the link I gave you for PO176 in your previous thread? Doesnt sound like you did.