Code P0190: rail pressure sensor circuit fault

Original definition (SAE J2012): Fuel Rail Pressure Sensor Circuit^[1][2][3][4]

• P0190Fuel rail pressure sensor circuit: circuit malfunction.
• P0191Fuel rail pressure sensor circuit: range or performance.^[6][8][9]
• P0192Fuel rail pressure sensor circuit: low input.^{[10][11][12][13]}

1. 1Faulty rail pressure sensor: it is the first cause on the list at Autodoc Club and Mechanic Base. On Volkswagen group vehicles, Ross-Tech identifies it as sensor G247.^{[1][2][14][15]}
2. 2Damaged sensor wiring, with a short circuit (Ross-Tech mentions a short to ground, at or near the sensor) or with deteriorated insulation.^{[1][2][14][15]}
3. 3Sensor connectors that are corroded, loose or making poor contact.^{[1][2][14][15]}
4. 4Faulty ECU: the three sources that mention it put it at the end of the list.^[1][2][15]
5. 5Fuel supply faults mentioned by Autodoc Club and PartsAvatar: fuel pump (or its relay), blocked filter, faulty pressure regulator, leaking lines or lack of fuel.^[1][14]

• Engine warning light (check engine light) on in the instrument cluster.^[2][14]Engine warning light: faults that cause it
• Long or difficult starting, with the engine cranking longer than normal before firing, or not starting at all.^[1][2][14]Hard to start: faults that cause it
• Rough idle.^[1][2]Vibrations: faults that cause it
• Loss of power.^[1][2]Less power: faults that cause it
• Jerking or hesitation when accelerating.^[1][14]Jerking: faults that cause it
• The car usually goes into limp mode, with engine speed and power limited.^[2]Limp mode: faults that cause it
• The engine may suddenly cut out while driving.^[1][2]Engine stalls: faults that cause it
• Increased fuel consumption.^[1]Uses more fuel: faults that cause it

1. 1Read the code and the freeze frame data with a diagnostic tool and see whether other codes are stored, especially rail pressure ones (P0191 to P0194, P0087, P0088), which rely on the signal from the same sensor.^[2][5][14]
2. 2Inspect the sensor connector (corrosion, loose pins, damage) and the wiring (insulation, chafing, sections touching ground). Cleaning and tightening the connections is the cheapest step and rules out a common cause.^{[1][2][14][15]}
3. 3With the diagnostic tool, compare the requested rail pressure with the one the sensor measures. According to Pico, a signal stuck at 0 V or 5 V indicates the sensor has failed; afterwards, it is worth confirming whether the origin is the sensor or its wiring.^[5][16]
4. 4With a multimeter, check at the connector that the sensor receives a clean 5 V reference supply and a good ground, and that the signal changes smoothly as the pressure varies. Also measure the sensor's resistance and compare with the manufacturer's values.^[2][16]
5. 5Check the wiring between the sensor and the ECU for an open circuit or a short to ground, measuring with the ECU connector disconnected.^[2][15]
6. 6Check the fuel supply: condition of the filter, operation of the pump and pressure measured with a gauge.^[1][14][16]
7. 7If the wiring, connector and supply are fine and the signal is still wrong, the main suspect is the sensor; the ECU is the last suspect.^[2][15]

Faults in which this code appears

• Medium severityFrequency: OccasionalVM Motori 2.8 and 3.0 CRDWear of the injectors and the high-pressure pumpThe injectors and common-rail pump of the 2.8 and the 3.0 V6 CRD can wear with the years: the sources place it between 120,000 and 180,000 km and describe it as loss of power or limp mode, not a widespread failure.Repair (garage): €800–€1,400Appears at around 120,000 km

• P0190 on Nissan5
• P0190 on Opel4