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Diagnostic Aids

Perform this test when directed by QUICK TEST. This test is intended to diagnose the following:

FRP SENSOR VOLTAGE-TO-FUEL PRESSURE CONVERSION

Volts psi (kPa)
4.5 70 (482)
3.9 60 (413)
3.4 50 (344)
2.8 40 (275)
2.2 30 (207)
1.6 20 (138)
1.1 10 (69
0.5 0.0 (.5)

  1. 1) KOEO & KOER DTC P0192: Verify DTC With FRP PID

    This DTC indicates FRP voltage fell below a minimum calibrated limit and a calibrated minimum amount of time during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • FRP Signal Shorted To SIG RTN Or PWR GND
    • Faulty FRP Sensor
    • Faulty PCM

    Turn ignition switch to ON position. Using scan tool, access FRP PID from PID/DATA MONITOR & RECORD menu. If FRP PID voltage is less than .2 volt, go to next step. If FRP PID voltage is .2 volt or more, go to step  11).

    NOTE: Fuel Rail Pressure (FRP) sensor may also be known as Injection Pressure (IP) sensor.

  2. 2) Generate Opposite Signal

    Turn ignition switch to OFF position. Disconnect FRP sensor connector. If scan tool communication problem exists, disconnect jumper wire and go to step  22). Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. If FRP V PID voltage is more than 4.6 volts, replace FRP sensor. If FRP V PID voltage is 4.6 volts or less, disconnect jumper wire and go to next step.

  3. 3) Check VREF Voltage To FRP Sensor

    Ensure FRP sensor is disconnected and ignition switch is turned to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN terminals. See Fig 1. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to TEST C, step  1).
    Fig 1: Identifying Fuel Rail Pressure (FRP) Sensor Circuits & Connector Terminals
    G99J02112Courtesy of FORD MOTOR CO.

  4. 4) Check FRP Circuit For Open In Harness

    Turn ignition switch to OFF position. Leave FRP sensor disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance between of FRP circuit between FRP sensor harness connector terminal and PCM harness connector terminal. See Fig 1. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FRP circuit.

  5. 5) Check FRP Circuit For Short To PWR GND Or SIG RTN

    Using a DVOM, measure resistance between PCM harness connector FRP and SIG RTN terminals. See Fig 1. Using a DVOM, measure resistance of FRP circuit between negative battery terminal and PCM harness connector terminal. If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit.

  6. 6) KOEO & KOER DTC P0193: Check FRP V PID Value

    This DTC indicates FRP voltage exceeded a maximum calibrated limit and a calibrated maximum amount of time during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • FRP Signal Shorted To VREF Or VPWR
    • FRP Signal Open
    • High Fuel Pressure (Possible Faulty Fuel Pressure Regulator - CNG)
    • Faulty FRP Sensor
    • Faulty PCM

    Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. FRP V PID voltage should be more than 4.8 volts. If FRP V PID voltage is as specified, go to next step. If FRP V PID voltage is not as specified, fault may be intermittent. Go to step  13).

  7. 7) Check FRP Sensor For Leaks

    Turn ignition switch to OFF position. Remove vacuum hose from FRP sensor. Inspect sensor and vacuum hose for fuel. If any fuel is present, replace FRP sensor. If no fuel is present, go to next step.

  8. 8) Simulate Opposite FRP Signal To PCM

    Turn ignition switch to OFF position. Disconnect FRP sensor connector. Connect jumper wire between FRP sensor harness connector FRP and SIG RTN terminals. See Fig 1. Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. If scan tool communication problem is present, disconnect jumper wire and go to step  22). If FRP V PID voltage is less than .2 volt, replace FRP sensor. If FRP V PID voltage is .2 volt or more, go to step  10).

  9. 9) KOEO & KOER DTC P0190: Check VREF Circuit To FRP Sensor

    DTC P0190 indicates FRP VREF voltage from PCM dropped below minimum calibrated voltage during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • VREF Open Circuit In Harness
    • VREF Open Circuit In Sensor
    • VREF Open Circuit In PCM

    Disconnect FRP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN terminals. See Fig 1. If voltage is 4-6 volts, go to step  11). If voltage is not 4-6 volts, go to next step.

  10. 10) Check FRP, SIG RTN & VREF Circuits For Opens

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of FRP, SIG RTN and VREF circuits between appropriate FRP sensor harness connector terminal and PCM harness connector terminal. See Fig 1. If all resistance measurements are less than 5 ohms, go to next step. If any resistance measurement is 5 ohms or more, repair open in affected FRP, SIG RTN or VREF circuit.

  11. 11) Using a DVOM, measure FRP Sensor Resistance

    Using a DVOM, measure resistance between FRP sensor FRP and SIG RTN terminals. See Fig 1. Using a DVOM, measure resistance between FRP sensor FRP and VREF terminals. FRP sensor resistance should be 30-40 k/ohms. If either resistance measurement is not within specification, replace FRP sensor. If both resistance measurements are within specification, proceed as follows:
    • If only Continuous Memory DTC P0190 is present, go to step  14).
    • If DTC P0192 is present, replace PCM.
    • If DTC P0193 is present, go to next step.

  12. 12) Check FRP Circuit For Short To VREF Or VPWR

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure between PCM harness connector FRP and VREF terminals. See Fig 1. Using a DVOM, measure resistance between PCM harness connector FRP and VPWR terminals. See PCM VPWR TERMINAL IDENTIFICATION  table. If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short in affected circuit.
    PCM VPWR TERMINAL IDENTIFICATION

    Application PCM Terminal No.
    All Models 71

  13. 13) Continuous Memory DTC P0190, P0192 & P0193: Check For Intermittent Fault

    Reconnect FRP sensor connector. Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. Observe FRP V PID voltage reading for fault while tapping on FRP sensor. Wiggle and bend wiring harness and connector between sensor and PCM. Fault will be indicated by a sudden change in PID voltage. If fault is indicated, isolate and repair as necessary. If fault is not indicated, symptom is intermittent and cannot be located at this time. Go to TEST Z, step  1) for additional test procedures.

  14. 14) KOEO, KOER & Continuous Memory DTC P0191: Check Fuel Pressure

    DTC P0191, P1168 or P1169 indicate fuel pressure fell below minimum or exceeded maximum calibrated limit for a calibrated period of time during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • High Fuel Pressure
    • Low Fuel Pressure
    • Excessive Resistance In Circuit
    • Faulty FRP Sensor
    • Low Or No Fuel

    Turn ignition switch to ON position. Ensure vehicle has fuel. Turn ignition switch to OFF position. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE procedure under FUEL SYSTEM in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Connect pressure gauge to Schrader valve on fuel rail. With engine running, check fuel pressure. Fuel pressure should be within specification. See FUEL PRESSURE SPECIFICATIONS  table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to TEST HC, step  1).

  15. 15) Check Fuel Pressure With FRP PID

    Connect scan tool to Data Link Connector (DLC). Ensure fuel pressure gauge is still connected. Turn ignition switch to ON position. Using scan tool, select FRP PID from PID/DATA MONITOR & RECORD menu. If FRP PID value is not within 10 psi of fuel pressure gauge measurement, go to next step. If FRP PID value is within 10 psi of fuel pressure gauge measurement, proceed as follows:
    • If DTC P1168 or DTC P1169 are present, clear DTCs. See CLEARING CODES  under SELF-DIAGNOSTIC SYSTEM. Road test vehicle 3-5 minutes at a steady speed. Stop vehicle and check for Continuous Memory DTCs. If DTC P1168 or DTC P1169 are still present, go to next step.
    • If any other DTC is present, repeat QUICK TEST .
    • If DTC P0191 is present in Continuous Memory, go to step  14).

  16. 16) Using a DVOM, measure VREF Voltage To FRP Sensor

    Disconnect FRP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN terminals. See Fig 1. If voltage is 4-6 volts, turn ignition switch to OFF position and go to next step. If voltage is not 4-6 volts, go to TEST C, step  1).

  17. 17) Check FRP Circuit For Excessive Resistance

    Ensure ignition switch is turned to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of FRP, SIG RTN and VREF circuits between appropriate FRP sensor harness connector terminal and PCM harness connector terminal. See Fig 1. If all resistance measurements are less than 5 ohms, go to next step. If any resistance measurement is 5 ohms or more, repair open in affected FRP, SIG RTN or VREF circuit.

  18. 18) Monitor FRP V PID With Scan Tool

    Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. If FRP V PID voltage is more than 4.8 volts on all other vehicles, replace FRP sensor. If FRP V PID voltage is not as specified, replace PCM.
    19. NOTE: When ALL ON is selected in OUTPUT TEST MODE, voltage measurement must be made within 7 seconds of activating test mode.

  19. 19) Check FSV VPWR To Fuel Rail Solenoid
    Disconnect fuel rail solenoid connector. Turn ignition switch to ON position. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE  under ADDITIONAL SYSTEM FUNCTIONS. Select outputs ALL ON. Using a DVOM, measure voltage between negative battery terminal and fuel rail solenoid harness connector FSV VPWR terminal (Pink/Black wire). See WIRING DIAGRAMS article. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in FSV VPWR circuit.

  20. 20) Check Ground Circuit For Open

    Using a DVOM, measure resistance between negative battery terminal and fuel rail solenoid harness connector ground terminal (Black wire). If resistance is less than 5 ohms, replace fuel rail solenoid. If resistance is 5 ohms or more, repair open in ground circuit.

  21. 22) Check VREF Voltage To FRP Sensor

    Disconnect FRP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN circuit terminals. If voltage is 4-6 volts, turn ignition switch to OFF position and go to next step. If voltage is not 4-6 volts, VREF is out of range. Go to TEST C, step  1).

  22. 21) Check For Shorted FRP Signal

    Disconnect scan tool from Data Link Connector (DLC). Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance between PCM harness connector FRP and SIG RTN terminals, between PCM harness connector FRP and VREF terminals, and between PCM harness connector FRP terminal and battery negative terminal. See WIRING DIAGRAMS article. If all resistance measurements are more than 10 k/ohms, replace PCM. If any resistance measurement is 10 k/ohms or less, repair short in affected circuit.
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