P1274 – Supply Pump Protection MMC L200 IV

FUNCTION

  • The engine-ECU monitors the signals input from the rail pressure sensor.
  • Based on these input signals, the engine-ECU checks whether the fuel pressure in the common rail is abnormal.

  • TROUBLE JUDGMENT

  • Engine is running
  • Rail pressure sensor is normal
  • For 1 seconds, the rail pressure stays in the critical pressure range in which the supply pump is burned out.

  • PROBABLE CAUSES

  • Failed supply pump
  • Failed common rail assembly
  • Failed engine-ECU

  • DIAGNOSIS PROCEDURE

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

    Q. Is any other diagnosis code than P1274 set?

    STEP 2. Check suction control valve itself

    Q. Is the check result normal?

    STEP 3. Replace the supply pump assembly.

  • After learning the supply pump assembly, re-check the trouble symptoms.
  • Q. Does trouble symptom persist?

    STEP 4. 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?

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