P0177 - Fuel Composition Sensor Circuit Range/Performance

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3

P0177 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
  • How do I fix code P0177

      Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

    P0177 Tech Notes

    Replaced Fuel Composition Sensor

    Cost of diagnosing the P0177 code

      Labor: 1.0

      The cost of diagnosing the P0177 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

    P0177 Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • P0177 Meaning

    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.

    P0177 More Information

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    P0177 Information for specific makes

  • P0177 MERCEDES-BENZ Fuel Composition Sensor Circuit Range/Performance