Code No. P0037: Oxygen Sensor (rear) Heater Circuit Low Input




OPERATION




FUNCTION




TROUBLE JUDGEMENT


Check Conditions
Judgement Criterion
Check Conditions
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. Perform resistance measurement at oxygen sensor (rear) connector.



  • Oxygen sensor (rear) connector check.
  • Disconnect connector, and measure at sensor side.
  • Resistance between terminal power supply line and engine-ECU OHRL line.
OK: 4.5 - 8.0 Ω (at 20°C)

Q. Is the check result normal?

Go to Step 2.
Repair or replace the connector, or replace the oxygen sensor (rear).

STEP 2. Perform voltage measurement at oxygen sensor (rear) connector.



  • Disconnect connector, and measure at harness side.
  • Power supply mode of electric motor switch: ACC
  • Voltage between terminal power supply line and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 3.

    Repair or replace the connector, or check and repair harness between oxygen sensor (rear) connector terminal and engine control relay connector terminal.

    • Check power supply line for open/short circuit.

STEP 3. Perform voltage measurement at engine-ECU connector.



  • Disconnect connector, and measure at harness side.
  • Power supply mode of electric motor switch: ACC
  • Voltage between terminal OHRL and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 4.

    Repair or replace the connector, or check and repair harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal OHRL.

    • Check earthing line for open/short circuit.

STEP 4. Check harness between oxygen sensor (rear) connector terminal and engine-ECU connector terminal OHRL.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 5.
Repair or replace the connector, or repair the damaged harness wire.

STEP 5. Check harness between oxygen sensor (rear) connector terminal and engine control relay connector terminal.



  • Check power supply 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. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.

Q. Is diagnosis code stored?

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