Code No. P0191: Rail Pressure Sensor Range/Performance Problem




OPERATION




FUNCTION




TROUBLE JUDGMENT


Check Condition
Judgment Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSTIC PROCEDURE


STEP 1. Check suction control valve itself.



  • Suction control valve connector check.
  • Check suction control valve itself (Refer to ).

Q. Is the check result normal?

Go to Step 2.
Repair or replace the connector, or replace the suction control valve.

STEP 2. Check harness between rail pressure sensor connector terminal and engine-ECU connector terminal FPSE.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 3.
Repair or replace the connector, or repair the damaged harness wire.

STEP 3. Check harness between rail pressure sensor connector terminal and engine-ECU connector terminal FPS5.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

STEP 4. Check harness between rail pressure sensor connector terminal and engine-ECU connector terminal FPS.



  • Check output line for damage.

Q. Is the check result normal?

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

STEP 5. Perform voltage measurement at rail pressure sensor connector.



  • Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
  • Engine: Idling (after warming up)
  • Voltage between terminal engine-ECU FPS line and body earth.
OK: 1.15 - 1.75 V

Q. Is the check result normal?

Replace the engine-ECU.
Replace the common rail assembly and fuel injection tubes.