Code No. P0088: Common Rail High Pressure Malfunction






OPERATION



  • Refer to Code No. P0628: Suction Control Valve Open <Euro3, Euro4> .
  • Refer to Code No. P0003: Suction Control Valve Open <Euro5> .

FUNCTION



  • The engine-ECU monitors the signals input from the rail pressure sensor.
  • Based on The input signals, the engine-ECU checks whether the fuel pressure in the common rail exceeds the maximum withstand pressure of the system.

TROUBLE JUDGMENT


Check Conditions
  • Rail pressure sensor is normal
  • Battery positive voltage is 8 - 16 V
Judgment Criterion
  • The rail pressure exceeds the threshold value of an abnormal high pressure for 3 seconds (continuous or accumulated).

PROBABLE CAUSES



  • Failed suction control valve
  • Failed engine-ECU

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is any other diagnosis code than P0088 set?
Inspection chart for diagnosis codes (Refer to ).
Go to Step 2 .

STEP 2. Check suction control valve itself.

  • Check suction control valve itself (Refer to ).

Q. Is the check result normal?
Go to Step 3 .
Replace the suction control valve. After replacing the suction control valve, learn the supply pump (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ).

STEP 3. Connector check: D-215 engine-ECU connector and B-129 suction control valve connector.

Q. Are the check results normal?
Go to Step 4 .
Repair or replace the connector then replace the common rail assembly and fuel injection tubes.

STEP 4. Check harness between D-215 (terminal No. 131) engine-ECU connector and B-129 (terminal No. 1) suction control valve connector.

  • Check power supply line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire then replace the common rail assembly and fuel injection tubes.

STEP 5. Check harness between D-215 (terminal No. 146) engine-ECU connector and B-129 (terminal No. 2) suction control valve connector.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire then replace the common rail assembly and fuel injection tubes.

STEP 6. Perform output wave pattern measurement at B-129 suction control valve (Using an oscilloscope).

  • Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
  • Engine: Idling
  • Connect the oscilloscope special patterns pickup to terminal No. 2 and earth.
OK: The waveform should show a pattern similar to the illustration of inspection procedure using an oscilloscope (Refer to ).

Q. Is the check result normal?
Go to Step 7 .
Replace the suction control valve then replace the common rail assembly and fuel injection tubes. After replacing the suction control valve, learn the supply pump (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ).

STEP 7. Replace the common rail assembly and fuel injection tubes.

  • After replacing the common rail assembly and fuel injection tubes, re-check the trouble symptoms

Q. Does trouble symptom persist?
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).
The check is end.