AutoCodes - Mercedes-benz - P0178 MERCEDES-BENZ

P0178 MERCEDES-BENZ Code - Fuel Composition Sensor Circuit Low Input

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3
Table of contents

|P0178 MERCEDES-BENZ code 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
  • Short to VPWR in FF sensor batte

|How do I fix the P0178 MERCEDES-BENZ code?

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.

|P0178 MERCEDES-BENZ code tech notes

Replaced Fuel Composition Sensor

|Cost of diagnosing the P0178 MERCEDES-BENZ code

Labor: 1.0

The cost of diagnosing the P0178 MERCEDES-BENZ code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|What are P0178 MERCEDES-BENZ code possible symptoms?

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

|P0178 MERCEDES-BENZ code 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.
OBDII Code P0178 Mercedes-benz - Fuel Composition Sensor Circuit Low Input - AutoCodes.com

|Need more information with the P0178 MERCEDES-BENZ code?

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|Need help with a P0178 MERCEDES-BENZ code?

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|P0178 MERCEDES-BENZ code comments

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