Fuel Pressure Sensors
The firmware provides separate low-pressure and high-pressure fuel sensor inputs. Both use a two-point linear calibration: raw voltage against known pressure at each endpoint (fluid-pressure initialization). Open Sensors > Fuel pressure and assign Fuel low pressure ADC input or Fuel high pressure ADC input, then enter their voltage and pressure points (fuel-pressure dialog).
Use the sensor datasheet or a trusted pressure reference. A reversed sensor is supported by entering its endpoints in the corresponding order. Verify Raw Low Fuel Pressure and the scaled low-pressure gauge first. High pressure is configured the same way but is displayed in bar; the HPFP controller consumes the high-pressure channel in kPa for closed-loop target control (HPFP feedback).
Rail-pressure selection
In Fuel > Injection configuration, Fuel rail pressure sensor selects which sensor represents injector pressure, and injector compensation can be set to sensed rail pressure. Sensor type in the fuel-pressure dialog distinguishes Absolute, Gauge, and Differential for the low-pressure/injector differential calculation. Absolute requires MAP. Gauge requires MAP plus barometric pressure, but a missing or out-of-range baro value is substituted with 101.325 kPa; differential is already a pressure difference (injector pressure math).
Wiring and diagnostics
The signal must use a board-supported analog input and the supply, ground, and interface required by the sensor. Do not assume that a generic analog pin accepts the transducer without board-level signal conditioning. Confirm the exact connector and revision from the board documentation.
The low-pressure input uses a 10 Hz filter; the high-pressure input uses 100 Hz. P0090 is emitted only when injector compensation is set to use a sensed rail pressure but the chosen fuel-pressure sensor has not been configured. If a configured sensor returns an invalid reading, the differential-pressure calculation returns no value and injector compensation falls back to 1.0 without that warning (missing-sensor warning, flow-ratio fallback). This revision does not map either fuel-pressure sensor to the normal value-based Sensor Checker DTC set; inspect raw voltage, scaled pressure, sensor supply, and calibration directly.