981 · Fuel

P0191

Fuel Rail Pressure Sensor Circuit Range/Performance

MED SEVERITY

The high-pressure fuel rail pressure sensor reading is implausible.

SYMPTOMS

  • Check-engine light
  • Rough idle or hesitation
  • Reduced performance
  • Worse fuel economy

LIKELY CAUSES

  • Faulty or drifting fuel rail pressure sensor
  • Wiring/connector fault
  • Mechanical/intake condition skewing the reading
  • ECM/PCM fault (rare)

DIAGNOSIS STEPS

  • Compare fuel rail pressure sensor live data against other sensors for plausibility
  • Inspect wiring and connector
  • Check for related mechanical causes (leaks, restriction)
  • Verify reference voltage and ground
  • Replace the sensor if out of spec

RELATED PARTS

  • Fuel rail pressure sensor
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