P0141
Heated Oxygen Sensor (rear) Heater Circuit:
Connectors:
CIRCUIT OPERATION
- Power is supplied from the MFI relay (terminal 4) to the heated oxygen sensor (rear) heater
- The ECM (terminal 54)
BACKGROUND
- The ECM
DTC SET CONDITIONS
Check Conditions
- 60 seconds have elapsed from the start of the previous monitoring.
- Engine coolant temperature is higher than 20 °C (68 °F).
- While the heated oxygen sensor (rear) heater is on.
- Battery positive voltage is at between 11 and 16 volts.
Judgment Criteria
- Heater current of the heated oxygen sensor (rear) heater has continued to be lower than 0.16 ampere or higher than 5.0 ampere for 4 seconds.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Open or shorted heated oxygen sensor (rear) heater circuit.
- Open circuit in heated oxygen sensor (rear) heater.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools
- MB991223: Test Harness Set
STEP 1. Check connector C-11 at the heated oxygen sensor (rear) for damage.
Q: Is the connector in good condition?
YES: Go to Step 2.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 2. Check the heated oxygen sensor (rear).
1. Disconnect heated oxygen sensor (rear) connector C-11 and connect test harness special tool, MB991223, to the connector on the heated oxygen (rear) sensor side.
2. Measure the resistance between heated oxygen sensor connector terminal 3 and terminal 4.
Standard value: 11 - 18 ohm [at 20 °C (68 °F)]
Q: Is the resistance normal?
YES: Go to Step 3.
NO: Replace the heated oxygen sensor (rear). Then go to Step 12.
STEP 3. Check the power supply voltage at heated oxygen sensor (rear) harness side connector C-11.
1. Disconnect the connector C-11 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 3 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 5.
NO: Go to Step 4.
STEP 4. Check harness connector B-12X at the MFI relay for damage.
Q: Is the connector in good condition?
YES: Check connector C-105 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector is in good condition, repair harness wire between MFI relay connector B-12X terminal 4 and heated oxygen sensor (rear) connector C-11 terminal 3 because of open circuit or short circuit to ground. Then go to Step 12.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 5. Check the power supply voltage at ECM connector C-117
1. Do not disconnect the connector C-117
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 54
- Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 8.
NO: Go to Step 6.
STEP 6. Check connector C-117 at ECM
Q: Is the connector in good condition?
YES: Go to Step 7.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 7. Check for open circuit and short circuit to ground between heated oxygen sensor (rear) connector C-11 terminal 4 and ECM connector C-117 terminal 54
Q: Is the harness wire in good condition?
YES: Replace the ECM or PCM. Then go to Step 12.
NO: Repair it. Then go to Step 12.
STEP 8. Check connector C-117 at ECM
Q: Is the connector in good condition?
YES: Go to Step 9.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.
STEP 9. Check for harness damage between MFI relay connector B-12X terminal 4 and heated oxygen sensor (rear) connector C-11 terminal 3.
NOTE: Check harness after checking intermediate connector C-105. If intermediate connectors is damaged, repair or replace it. Refer to
Harness Connector Inspection. Then go to Step 12.
Q: Is the harness wire in good condition?
YES: Go to Step 10.
NO: Repair it. Then go to Step 12.
STEP 10. Check for harness damage between heated oxygen sensor (rear) connector C-11 terminal 4 and ECM connector C-117 terminal 54
Q: Is the harness wire in good condition?
YES: Go to Step 11.
NO: Repair it. Then go to Step 12.
STEP 11. Check the trouble symptoms.
1. Carry out a test drive with the drive cycle pattern. Refer to, Procedure 6 - Other Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0141 output?
YES: Replace the ECM or PCM. Then go to Step 12.
NO: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.
STEP 12. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to, Procedure 6 - Other Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0141 output?
YES: Retry the troubleshooting.
NO: The inspection is complete.