Code Definition

P1191 — Fuel Rail Pressure Sensor Circuit Low Input

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Opel

About P1191

P1191 is a manufacturer-specific powertrain diagnostic trouble code recorded for Opel vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1191 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1191 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The fuel rail pressure (FRP) sensor reports the pressure in the fuel rail to the engine control module as a varying voltage, typically riding on a 5V reference, so the ECM can run closed loop fuel pressure control. DTC P1191 sets when the ECM sees the FRP sensor signal voltage drop below its normal range, a low input. This can mean the circuit itself is faulty, for example the signal wire shorted to ground or an open reference, or that the sensor is genuinely reporting very low fuel pressure. The distinction matters, because a wiring or sensor fault is repaired very differently from a real fue...

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