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P0191Cars & SUVs
Moderate

P0191 — Fuel rail pressure sensor circuit — out of range

The common-rail fuel pressure sensor is reporting an inconsistent value. On modern truck diesels, that hits fuel injection and power directly.

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Likely causes

  • Faulty rail pressure sensor
  • Internal or external leak on the common rail
  • Wiring issue or corroded connector on the sensor circuit

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Recommended checks

  1. 1

    Measure actual rail pressure with a gauge and compare to the sensor

  2. 2

    Inspect the rail and injectors for fuel leaks

  3. 3

    Replace the pressure sensor if the mismatch is confirmed

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Parts to replace