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2013 SUBARU TRIBECA
3.6L H6•AWD•AUTOMATIC•gas
6 active safety recalls on this vehicle — view recalls
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Repairs0Labor478Torque3345Fluid10DTC1861Battery1Maintenance0Recalls6
P0178moderate severityPowertrain

Fuel Composition Sensor Circuit Low

on 2013 Subaru Tribeca 3.6L H6 · AWD

What this code means

The PCM detects a low voltage signal from the fuel composition (flex fuel) sensor circuit. This sensor measures the ethanol content of the fuel.

Symptoms

  • Check engine light on
  • Poor performance on flex fuel
  • Reduced fuel economy

Common causes

  • Faulty flex fuel sensor
  • Short to ground in wiring
  • Corroded connector
  • Faulty PCM

Diagnostic steps

  1. Scan for stored codes and freeze frame
  2. Check flex fuel sensor signal voltage
  3. Inspect wiring for shorts to ground
  4. Replace fuel composition sensor if faulty
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