Code No. P0137: Oxygen Sensor (rear) Circuit Low Voltage




OPERATION




FUNCTION




TROUBLE JUDGMENT


Check Conditions
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


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



  • Data list reference table (Refer to ).

  1. Item AD: 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. Perform voltage measurement at oxygen sensor (rear) connector.



  • Disconnect connector, and measure at harness side.
  • Ignition switch: "ON"
  • Voltage between terminal engine-ECU ORLE line and body earth.
OK: 0.4 - 0.6 V

Q. Is the check result normal?

Go to Step 5.
Go to Step 3.

STEP 3. Check harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal ORLE.



  • Check earthing line for open circuit.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

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



  • Data list reference table (Refer to ).

  1. Item AD: 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.

STEP 5. Check harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal ORLE.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 6.
Repair or replace the connector, or repair the damaged harness wire.

STEP 6. Perform voltage measurement at oxygen sensor (rear) connector.



  • Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
  • Transmission: 2nd speed
  • Drive with wide open throttle
  • Engine: 3,500 r/min or more
  • Voltage between terminal engine-ECU O2RL line and body earth.
OK:
    The output voltage should be 1.1 - 1.5 V.

Q. Is the check result normal?

Go to Step 8.
Go to Step 7.

STEP 7. Check oxygen sensor (rear) itself.



  • Oxygen sensor check (Refer to ).

Q. Is the check result normal?


    Repair or replace the connector, or check intermediate connectors, and repair if necessary. If intermediate connectors are normal, check and repair harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal O2RL.

    • Check output line for short circuit.
Replace oxygen sensor (rear).

STEP 8. Check harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal O2RL.



  • Check output line for open circuit and damage.

Q. Is the check result normal?

Go to Step 4.
Repair the damaged harness wire.