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P0176 OBD-II Trouble Code: Fuel Composition Sensor Circuit

Check Engine Light

P0176 code definition?

Fuel Composition Sensor Circuit Malfunction

What the P0176 code means

Trouble code P0176 is triggered by the Engine Control Module (ECM) when it receives an abnormal signal from the flex fuel sensor.

The flex fuel sensor is designed to measure the amount of ethanol present in the gasoline of a flexible-fuel vehicle (FFV); some ethanol is added to the gasoline because it is a renewable resource, and it burns off less pollutants. The flex fuel sensor sends a signal to the ECM in correlation with the amount of ethanol present, then the ECM adjusts the ignition timing and fuel injector pulse width accordingly.

What causes the P0176 code?

  • Contaminated or incorrect fuel
  • Faulty flex fuel sensor
  • Open or short in flex fuel sensor circuit
  • Faulty ECM
  • Damaged flex fuel sensor line

What are the symptoms of the P0176 code?

  • The Check Engine Light will set
  • The engine may stall

How does a mechanic diagnose the P0176 code?

  • Inspects the quality and clarity of the gasoline
  • Tests the circuit of the flex fuel sensor with a digital multimeter
  • Inspects the wiring and electrical terminals of the flex fuel sensor
  • Inspects the fuel lines
  • Checks the fuel pressure

Common mistakes when diagnosing the P0176 code

Not checking for fuel flow restrictions

How serious is the P0176 code?

May cause the engine to stall, which may leave you stranded or having to wait for assistance

What repairs can fix the P0176 code?

  • Exchanging of contaminated or incorrect fuel
  • Replacing a faulty flex fuel sensor
  • Repairing an open or short in the flex fuel sensor circuit
  • Replacing a faulty ECM
  • Replacing a damaged or pinched flex fuel sensor line

Need help with a P0176 code?

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