Code No. P0158: Left Bank Oxygen Sensor (Rear) Circuit High Voltage








OPERATION



  • The sensor signal is inputted to the engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 116) from the left bank oxygen sensor (rear) output terminal (terminal No. 4).
  • The left bank oxygen sensor (rear) (terminal No. 2) is earthed with engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 96).

FUNCTION



  • The left bank oxygen sensor (rear) converts the concentration of oxygen in the exhaust emission into a voltage and inputs the signal to the engine-ECU <M/T> or engine-A/T-ECU <A/T>.
  • When the air-fuel ratio is richer than the theoretical air-fuel ratio, the left bank 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 <M/T> or engine-A/T-ECU <A/T> controls the fuel injection amount so that the air-fuel ratio can be equivalent to the theoretical air-fuel ratio.

TROUBLE JUDGMENT


Check Condition
  • Above 2 seconds later after the engine has started up.
Judgment Criterion
  • Left bank oxygen sensor (rear) output voltage is 1.2 V or more for 2 seconds.

PROBABLE CAUSES



  • Short circuit in left bank oxygen sensor (rear) circuit or loose connector contact
  • Failed engine-ECU <M/T> or engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

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

  • Refer to Data List Reference Table .

  1. Item AF: Left bank oxygen sensor (rear)

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. Connector check: C-02 left bank oxygen sensor (rear) connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Connector check: D-246 engine-ECU <M/T> connector or D-217 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?
Go to Step 4 .
Repair or replace the connector.

STEP 4. Check harness between C-02 (terminal No. 4) left bank oxygen sensor (rear) connector and D-246 (terminal No. 116) engine-ECU <M/T> connector or D-217 (terminal No. 116) engine-A/T-ECU <A/T> connector.
note Before checking harness, check intermediate connector D-225, and repair if necessary.

  • Check output line for short circuit.

Q. Is the check result normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. Check harness between C-02 (terminal No. 2) left bank oxygen sensor (rear) connector and D-246 (terminal No. 96) engine-ECU <M/T> connector or D-217 (terminal No. 96) engine-A/T-ECU <A/T> connector.
note Before checking harness, check intermediate connectors D-111 and D-225, and repair if necessary.

  • Check earthing line for short circuit.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.

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

  • Refer to Data List Reference Table .

  1. Item AF: Left bank oxygen sensor (rear)

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 <M/T> or engine-A/T-ECU <A/T>.