[amidgeha]

Fuel Composition Sensor Circuit Range/Performance

Fuel Composition Sensors are used to determine the amount of ethanol alcohol in the gasoline. Normally, a gasoline engine should not have more than 10% ethanol alcohol in the fuel for proper operation. Some vehicles have a Flexible Fuel (FF) system on them that allow them to run on up to 85% ethanol alcohol in the fuel. The fuel composition sensor sends a frequency modulated signal to the engine controller which is proportional to the alcohol content of the fuel. The injector pulse width and the ignition timing are modified for the increased alcohol content. It takes almost twice the amount of alcohol compared to gasoline to produce the same power.

Cause:
Flexible Fuel (FF) sensor to Vehicle Power (VPWR) circuit harness open or shorted
FF to VPWR circuit poor electrical connection
Open in FF sensor signal circuit
Short to ground in FF sensor signal circuit
Fuel contamination

Symptoms:
Check engine light