Posted in Mitsubishi Colt

P0136 – Oxygen Sensor (Rear) System MMC Colt

 Posted by  Posted on September 26, 2020

OPERATION

  • The sensor signal is inputted to the engine-ECU (terminal No. 100) from the oxygen sensor (rear) output terminal (terminal No. 1).
  • The oxygen sensor (rear) (terminal No. 2) is earthed with engine-ECU (terminal No. 99).

    • FUNCTION

  • The oxygen sensor (rear) converts the concentration of oxygen in the exhaust emission into a voltage and inputs the signal to the engine-ECU.
  • When the air-fuel ratio is richer than the theoretical air-fuel ratio, the oxygen sensor (rear) outputs a voltage of about 1 V. When it is leaner than the theoretical air-fuel ratio, it outputs a voltage of about 0 V.
  • Based on this signal, the engine-ECU corrects the deviation in the signal that is output by the oxygen sensor (front).

    • TROUBLE JUDGMENT

  • Above 3 minutes later after the engine has started up.
  • The engine coolant temperature is approximately 82°C or higher.
  • The engine speed is 1200 r/min or more.
  • The monitoring time is 10 seconds.
  • When the oxygen sensor (rear) output voltage is 0.2 V or less and a power voltage of 5 V is applied to the oxygen sensor (rear) in the engine-ECU, the sensor output voltage is 4.5 V or more.
  • To be monitored once per driving cycle.
  • 2 seconds later after lack of circuit continuity is detected.
  • When the front oxygen sensor is normally operated.
  • When the air-fuel ratio is rich, the oxygen sensor (front) output voltage is 0.5 V or more.
  • The oxygen sensor (rear) output voltage is less than 0.1 V.
  • The difference between the maximum and the minimum of the oxygen sensor (rear) output is 0.078 V or less.

    • PROBABLE CAUSES

  • Failed oxygen sensor (rear)
  • Open or shorted oxygen sensor (rear) circuit, harness damage, or connector damage
  • Failed engine-ECU

    • DIAGNOSIS PROCEDURE

    STEP 1. M.U.T.-III data list

  • Item No. 10: Oxygen sensor (rear)

    • Q. Is the check result normal?

    STEP 2. Connector check: C-24 oxygen sensor (rear) connector

    Q. Is the check result normal?

    STEP 3. Perform resistance measurement at C-24 oxygen sensor (rear) connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 2 and earth.

    • Q. Is the check result normal?

    STEP 4. Connector check: A-09 engine-ECU connector

    Q. Is the check result normal?

    STEP 5. Check harness between C-24 (terminal No. 2) oxygen sensor (rear) connector and A-09 (terminal No. 99) engine-ECU connector.

  • Check earthing line for open circuit and damage.

    • Q. Is the check result normal?

    STEP 6. M.U.T.-III data list

  • Item No. 10: Oxygen sensor (rear)

    • Q. Is the check result normal?

    STEP 7. Perform voltage measurement at C-24 oxygen sensor (rear) connector.

  • Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
  • Engine: After warm-up
  • Transmission: Neutral
  • Voltage between terminal No. 1 and earth.

    • Q. Is the check result normal?

    STEP 8. Check Oxygen sensor (rear) itself.

    Q. Is the check result normal?

    STEP 9. Connector check: A-09 engine-ECU connector

    Q. Is the check result normal?

  • Check output line for short circuit.

    • STEP 10. Perform voltage measurement at A-09 engine-ECU connector.

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB991987), and then measure the voltage on the check connector.
  • Transmission: Neutral
  • Engine: After warm-up
  • Voltage between terminal No. 100 and earth.

    • Q. Is the check result normal?

    STEP 11. Connector check: A-09 engine-ECU connector

    Q. Is the check result normal?

  • Check output line for open circuit and damage.

    • STEP 12. Connector check: A-09 engine-ECU connector

    Q. Is the check result normal?

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