Code No. P0192: Rail Pressure Sensor Circuit Low Input




OPERATION



  • A power voltage of 5 V is applied to the rail pressure sensor power terminal from the engine-ECU connector terminal FPS5 and earthed to the engine-ECU connector terminal FPSE from the rail pressure sensor connector terminal.
  • The sensor signal is inputted to the engine-ECU connector terminal FPS from the rail pressure sensor output terminal.

FUNCTION



  • The rail pressure sensor converts the rail pressure into a voltage signal and inputs the signal to the engine-ECU.
  • In response to the signal, the engine-ECU corrects the fuel injection quantity.

TROUBLE JUDGMENT


Check Conditions
  • Battery positive voltage is 8 - 16 V
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
Judgment Criterion
  • The rail pressure sensor output voltage is 0.70 V or less.

FAIL-SAFE AND BACKUP FUNCTION



  • The rail pressure is controlled in the range between 50 and 100 MPa.
  • The fuel injection amount is restricted (Output restriction).
  • The open angle of the accelerator pedal is restricted.
  • The throttle valve is closed (Fixed opening degree).
  • The EGR control is stopped (fully closed).
  • The DPF regeneration is prohibited.
  • The AS&G control is prohibited.

PROBABLE CAUSES



  • Failed rail pressure sensor
  • Open/short circuit or harness damage in rail pressure sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III data list



  • Refer to Data List Reference Table .

  1. Item 63: Rail pressure sensor

Q. Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2.

STEP 2. Perform resistance measurement at fuel pressure sensor connector.



  • Disconnect connector, and measure at harness side.
  • Resistance between terminal engine-ECU FPS line and body earth.
OK: No continuity

Q. Is the check result normal?

Go to Step 4.
Go to Step 3.

STEP 3. Check harness between rail pressure sensor connector terminal and engine-ECU connector terminal FPS.



  • Check output line for short circuit.

Q. Is the check result normal?

Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 4. Voltage measurement at rail pressure sensor connector.



  • Disconnect connector, and measure at sensor side.
  • With the special tool test harness (MB991658) bridge only the mating terminals of engine-ECU FPS5 line and engine-ECU FPSE line of the disconnected connector.
  • Ignition switch: ON
  • Voltage between terminal engine-ECU FPS line and body earth.
OK: 0.85 V or more

Q. Is the check result normal?

Go to Step 5.
Replace the rail pressure sensor.

STEP 5. M.U.T.-III data list



  • Refer to Data List Reference Table .

  1. Item 63: Rail pressure sensor

Q. Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.