Posted in Mitsubishi Colt

P0140 – Oxygen Sensor (rear) Circuit No Activity Detected 3A9 MMC Colt

 Posted by  Posted on September 26, 2020

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.
  • In response to the signal, the engine-ECU controls the fuel injection amount so that the air-fuel ratio can be equivalent to the theoretical air-fuel ratio.

    • TROUBLE JUDGMENT

  • Engine coolant temperature is more than 76°C.
  • Oxygen sensor (front) is active.
  • Repeat 1 time or more: drive*1, stop*2.
  • Engine speed is more than 1,500 r/min.
  • Manifold absolute pressure is more than 53 kPa.
  • Vehicle speed is more than 30 km/h.
  • A total of more than 60 seconds have passed with the above mentioned conditions, and more than 3 seconds have passed with the fuel shut off.
  • Vehicle speed is less than 1.5 km/h.
  • Change in the output voltage of the oxygen sensor (rear) is less than 0.098 volt.
  • The maximum output voltage of the oxygen sensor (rear) is less than 0.508 volt.
    note Monitoring stops after fuel has been shut off for 64 seconds or more.

    • PROBABLE CAUSES

  • Failed oxygen sensor (rear)
  • Harness damage in oxygen sensor (rear) circuit
  • 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. Replace the oxygen sensor (rear)

  • After replacing the oxygen sensor (rear), reconfirm whether the diagnosis code is set.

    • Q. Is the diagnosis code set?

    Author: admin