P0401 – EGR Flow Insufficient MMC L200 IV

FUNCTION

  • The engine-ECU monitors the EGR flow rate.

  • TROUBLE JUDGEMENT

  • Engine is running.
  • Battery positive voltage is 8 – 16 V.
  • Normal running (vehicle speed: 65 – 75 km/h, transmission: 5th <M/T>, D range <A/T>).
  • The intake air temperature is from 20 to 40 °C.
  • The EGR flow rate is larger than target EGR flow rate by the rate that is more than the specified value.

  • PROBABLE CAUSES

  • Failed EGR passage (leakage and clogged EGR passage)
  • Harness damage in EGR valve circuit or loose connector contact
  • Failed EGR valve operation
  • Harness damage in air flow sensor circuit or loose connector contact
  • Failed air flow sensor (abnormal output characteristics)
  • Failed engine-ECU

  • DIAGNOSIS PROCEDURE

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

    Q. Is diagnosis code P0403 or P2413 stored?

    STEP 2. Connector check: A-45 EGR valve assembly connector

    Q. Is the check result normal?

    STEP 3. Connector check: C-103 and C-105 engine-ECU connectors

    Q. Is the check result normal?

    STEP 4. Check harness between C-103 (terminal No. 115) engine-ECU connector and A-45 (terminal No. 6) EGR valve assembly connector.

  • Check output line for damage.
  • Q. Is the check result normal?

    STEP 5. Check harness between C-103 (terminal No. 130) engine-ECU connector and A-45 (terminal No. 4) EGR valve assembly connector.

  • Check output line for damage.
  • Q. Is the check result normal?

    STEP 6. Check harness between C-105 (terminal No. 81) engine-ECU connector and A-45 (terminal No. 2) EGR valve assembly connector.

  • Check earthing line for damage.
  • Q. Is the check result normal?

    STEP 7. Check harness between C-105 (terminal No. 71) engine-ECU connector and A-45 (terminal No. 3) EGR valve assembly connector.

  • Check power supply line for damage.
  • Q. Is the check result normal?

    STEP 8. Check harness between C-105 (terminal No. 57) engine-ECU connector and A-45 (terminal No. 1) EGR valve assembly connector.

  • Check output line for damage.
  • Q. Is the check result normal?

    STEP 9. Check EGR valve itself.

    Q. Is the check result normal?

    STEP 10. Check EGR passage for deposits.

    Q. Is the check result normal?

    STEP 11. Connector check: A-135 air flow sensor connector.

    Q. Is the check result normal?

    STEP 12. Check harness between A-135 (terminal No. 4) air flow sensor connector and C-103 (terminal No. 155) engine-ECU connector.

  • Check earthing line for damage.
  • Q. Is the check result normal?

    STEP 13. Check harness between A-135 (terminal No. 3) air flow sensor connector and C-103 (terminal No. 140) engine-ECU connector.

  • Check output line for damage.
  • Q. Is the check result normal?

    STEP 14. Replace the air flow sensor.

  • After replacing the air flow sensor, re-check the trouble symptoms.
  • Q. Is the check result normal?

    Author: admin