Racetronix Genuine GM / CONTI Flex-Fuel Sensors for E85


Modern technological advances have given racers alternative sources for fuel; from ethanol to pump gas, to methanol 116-octange race fuel. Of course, there are those of us who like to run a mixture or even straight ethanol in their vehicle. Most modern vehicles have the ability to switch between E85 or typical 93-octane gasoline. Since our friends at Racetronix offers everything you need to build a killer fuel system for your ride, no matter the setup, they figured it only made sense to offer the GM-CONTI Flex-Fuel Sensors as well. Read more below!

Official Release:


Racetronix now stocks genuine GM/Conti Flex-Fuel (E85) sensors in both the small and standard package sizes. The flex fuel sensor measures the ethanol-gasoline ratio of the fuel being used in a flexible fuel vehicle. Flexible fuel vehicles can be operated with a blend of ethanol and gasoline, up to 85 percent ethanol. In order to adjust the ignition timing and the fuel quantity to be injected, the engine management system requires information about the percentage of ethanol in the fuel. The flex fuel sensor uses quick-connect style fuel connections, an incoming fuel connection, and an outgoing fuel connection.

All fuel passes through the flex fuel sensor before continuing on to the fuel rail. The flex fuel sensor measures the fuel alcohol content, and sends an electrical signal to the engine control module (ECM) to indicate ethanol percentage.

The flex fuel sensor has a three-wire electrical harness connector. The three wires provide a ground circuit, a power source, and a signal output to the ECM. The power source is battery positive voltage and the ground circuit connects to an engine ground. The signal circuit carries the ethanol percentage via a frequency signal. Alcohol content information is supplied to the ECM from the fuel composition sensor.

The fuel composition sensor has a battery positive circuit, a signal circuit, and a ground circuit. The fuel composition sensor uses a microprocessor inside the sensor to measure the ethanol percentage and changes the output signal accordingly. The signal circuit carries the ethanol percentage via the frequency signal. The ECM provides an internal pull up to 5V on the signal circuit, and the fuel composition sensor pulls the 5V to ground in pulses. The normal range of operating frequency is between 50–150Hz. The microprocessor inside the sensor is capable of a certain amount of self-diagnosis. An output frequency between 180Hz and 190Hz indicates that the fuel is contaminated.

Please check out our QDA quick-disconnect adapters such as our crescent-lock 3/8″ double ended female and our 3/8″ quick-disconnect Teflon hose ends to simplify installation of these sensors.


  • OEM quality component
  • Provides the ability to run E85
  •  Quick-connect style fuel connections
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