Code No. P0153: Left Bank Oxygen Sensor (front) Circuit Slow Response








OPERATION



  • The sensor signal is inputted to the engine-ECU (terminal No. 38) from the left bank oxygen sensor (front) output terminal (terminal No. 4).
  • The left bank oxygen sensor (front) (terminal No. 2) is earthed with engine-ECU (terminal No. 39).

FUNCTION



  • The left bank oxygen sensor (front) 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 left bank oxygen sensor (front) 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


Check Conditions
  • Engine coolant temperature is higher than 50°C.
  • Engine speed is 1,250 - 3,500 r/min.
  • Volumetric efficiency is 25 - 65 %.
  • Under the closed loop air/fuel control.
  • The accelerator pedal is open.
  • Short-term fuel trim is -25 to +25 %.
  • More than 2 seconds have elapsed after the abovementioned conditions have been met.
  • The engine-ECU monitors for this condition for 5 cycles of 12 seconds each during the drive cycle.
Judgment Criterion
  • The average of the left bank oxygen sensor (front) rich/lean switching frequency is less than 11 times per 12 seconds.

PROBABLE CAUSES



  • Failed left bank oxygen sensor (front)
  • Loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

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

  • Refer to Data List Reference Table .

  1. Item AE: Left bank oxygen sensor (front)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2 .

STEP 2. Check left bank oxygen sensor (front) itself.



  • Check left bank oxygen sensor (front) itself (Refer to ).

Q. Is the check result normal?
Go to Step 3 .
Replace the left bank oxygen sensor (front).

STEP 3. Connector check: B-40 left bank oxygen sensor (front) connector and B-29 engine-ECU connector

Q. Are the check results normal?
Go to Step 4 .
Repair or replace the connector.

STEP 4. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item AE: Left bank oxygen sensor (front)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.