P1273 – Supply Pump Insufficient Flow MMC L200 IV


  • The engine-ECU controls the fuel discharge rate using the suction control valve.
  • The engine-ECU monitors changes in the fuel discharge rate at each injection to detect a fault in one of the two plungers in the supply pump.


  • Vehicle in steady and stable state (the difference from the last data of the objective common rail pressure is less than 3 MPa and that from the last data of the final fuel injection rate is less than 2 mm3/st.
  • The inter-cylinder difference in pressure feed exceeds the predetermined value 500 times consecutively.


  • Air penetration due to lack of fuel
  • Failed supply pump
  • Failed engine-ECU


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

  • With the air released from the fuel line, supply fuel if necessary.
  • Continue idle operation for about 5 minutes.
  • Q. Is diagnosis code P1273 set again?

    STEP 2. Replace the supply pump assembly.

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

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