OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P0191

Fuel Rail Pressure Sensor Circuit Range / Performance

The fuel rail pressure sensor signal is within electrical limits but doesn't match commanded rail pressure under various engine loads. Common in common-rail diesel and GDI petrol engines.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 91

Possible causes

  • Pressure sensor drifted high
  • Pressure regulator stuck medium
  • High-pressure pump worn low

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 200–1500 €
  • Estimated time: 1–6 h
  • Component: fuel rail pressure sensor
  • Component: high pressure pump
  • Component: rail pressure regulator
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication