P0177 Toyota Fuel Composition Sensor Circuit Range/Performance
Possible causes
– 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
– FF to VPWR circuit poor electrical connection
– Open in FF sensor signal circuit
– Short to ground in FF sensor signal circuit
– Fuel contamination
Tech description
Replaced Fuel Composition Sensor
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0177 Toyota Description
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.
Toyota Vehicle:Toyota Prius,Toyota Celica,Toyota Supra,Toyota Carina,Toyota Camry,Toyota MR2,Toyota Aygo,Toyota 4Runner,Toyota Avalon,Toyota Camry,Toyota Corolla,Toyota FJ Cruiser,Toyota Highlander,Toyota Land Cruiser,Toyota Matrix,Toyota Prius,Toyota RAV4,Toyota Sequoia,Toyota Sienna,Toyota Solara,Toyota Tacoma,Toyota Tundra,Toyota Yaris,