Ford Mustang 1999-2005

Fuel Rail Pressure & Temperature (FRPT) Sensor



The FRPT sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to pressure.

Strain gauge type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The FRPT sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each engine combustion cylinder.

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Fig. Fuel Rail Pressure and Temperature (FRPT) Sensor

Removal & Installation

Do not smoke, carry lighted tobacco or have an open flame of any type when working on or near any fuel-related component. Highly flammable mixtures are always present and may be ignited. Failure to follow these instructions may result in serious personal injury.

Before working on or disconnecting any of the fuel tubes or fuel system components, relieve the fuel system pressure to prevent accidental spraying of fuel. Fuel in the fuel system remains under high pressure, even when the engine is not running. Failure to follow this instruction may result in serious personal injury.

  1. Release the fuel system pressure.
  3. Disconnect the battery ground cable.
  5. Disconnect the fuel rail pressure and temperature sensor electrical connector.
  7. Disconnect the vacuum hose from the fuel rail pressure and temperature sensor.
  9. Remove the 2 bolts and the fuel rail pressure and temperature sensor.
    1. To install, tighten to 53 inch lbs. (6 Nm).

  11. To install, reverse the removal procedure.
  13. Inspect the O-ring seal and install new as necessary.
  15. Lubricate the O-ring seal with clean engine oil.


With the engine running, the FRPT PID value may be 48-70 kPa (7-10 psi) higher than a fuel pressure reading taken with a mechanical gauge.

FRPT Sensor Pin testing

For reference values, refer to PCM testing-PCM reference voltage pin chart

This pinpoint test is intended to diagnose the following:

Fuel Rail Pressure Temperature (FRPT) sensor (9G756)
Harness circuits: FRPT

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Fig. FRPT Sensor tables and graphs