P0161

Left Bank Heated Oxygen Sensor (rear) Heater Circuit:

Connectors:

CIRCUIT OPERATION
- Power is supplied from the MFI relay (terminal 1) to the left bank heated oxygen sensor (rear) heater.
- The PCM (terminal 26) controls continuity to the left bank heated oxygen sensor (rear) heater by turning the power transistor in the PCM "ON" and "OFF".

BACKGROUND
- The PCM checks whether the heater current is within a specified range when the heater is energized.

DTC SET CONDITIONS

Check Area
- Engine coolant temperature is higher than 20° C (68° F).
- The left bank heated oxygen sensor (rear) heater remains ON.
- Battery voltage is between 11 and 16 volts.

Judgment Criteria
- Heater current of the left bank heated oxygen sensor (rear) heater has continued to be lower than 0.2 ampere or higher than 3.5 ampere for 6 seconds.
- Only one monitor during one drive cycle.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Open or shorted left bank heated oxygen sensor (rear) heater circuit.
- Open circuit in left bank heated oxygen sensor (rear) heater.
- PCM failed.

DIAGNOSIS




STEP 1. Check the left bank heated oxygen sensor (rear).
1. Disconnect the left bank heated oxygen sensor (rear) connector E-48.

2. Measure resistance between the left bank heated oxygen sensor (rear) side connector terminals 1 and 3.
- Resistance should be between 7 and 40 ohms.

If within specifications, go to Step 2.

If not within specifications, replace the left bank heated oxygen sensor (rear). Then go to Step 5.




STEP 2. Check the power supply line at the left bank heated oxygen sensor (rear) connector E-48.
1. Disconnect connector E-48 and measure at the harness side.
2. Turn the ignition switch "ON".

3. Connect terminal 1 and the ground via a 20-ohms resistor.
Measure the current at this time.
- The current should be 0.5 ampere or more.

4. Turn the ignition switch "OFF".

If within specifications, go to Step 3.

If not within specifications, check the intermediate connectors C-14, C-79 and E-45, and repair or replace as required. Refer to vehicle level Testing and Inspection. If the intermediate connectors C-14, C-79 and E-45 are in good condition, repair the harness wire between the MFI relay connector C-59 and the left bank heated oxygen sensor (rear) connector E-48. Then go to Step 5.







STEP 3. Check the harness wire between the left bank heated oxygen sensor (rear) connector E-48 and the PCM connector C-89.
NOTE: After inspecting the intermediate connectors C-79 and E-45, inspect the wire. If the intermediate connector C-79 and E-45 are damaged, repair or replace it Refer to vehicle level Testing and Inspection. Then go to Step 5.

If the wire between the left bank heated oxygen sensor (rear) connector E-48 and the PCM connector C-89 is not damaged, go to Step 4.

If the wire between the left bank heated oxygen sensor (rear) connector E-48 and the PCM connector C-89 is damaged, repair it. Then go to Step 5.







STEP 4. Check for damage of the harness connector E-48 at the left bank heated oxygen sensor (rear) and the harness connector C-89 at the PCM.

If harness connectors E-48 and C-89 are damaged, repair or replace them. Refer to vehicle level Testing and Inspection.

If harness connectors E-48 and C-89 are in good condition, replace the PCM.

Then go to Step 5.

STEP 5. Test the OBD-II drive cycle
1. Carry out a test drive with the drive cycle pattern.Refer to Procedure 6 - Other Monitor.

2. Read the diagnostic trouble code, and confirm that a diagnostic trouble code is not being output.