P0141
DTC P0141: Heated Oxygen Sensor Heater CircuitHeated Oxygen Sensor (rear) Heater Circuit Part 1:
Heated Oxygen Sensor (rear) Heater Circuit Part 2:
CIRCUIT OPERATION
- Power is supplied from the MFI relay (terminal No. 4) to the heated oxygen sensor (rear) heater.
- The ECM (terminal No. 54) controls continuity to the heated oxygen sensor (rear) heater by turning the power transistor in the ECM "ON" and "OFF".
BACKGROUND
- The ECM checks whether the heater current is within a specified range when the heater is energized.
DESCRIPTIONS OF MONITOR METHODS
- Heated oxygen sensor heater (rear) current is out of specified range when engine coolant temperature is over 20 °C (68 °F).
MONITOR EXECUTION
- Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Engine coolant temperature sensor
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
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 16.5 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.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Open or shorted heated oxygen sensor (rear) heater circuit, or harness damage.
- Open circuit in heated oxygen sensor (rear) heater.
- Connector damage.
- ECM failed.
DIAGNOSIS
Required Special Tool:
- MB991658: Test Harness Set
STEP 1. Check connector D-40 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 D-40 and connect test harness special tool, MB991658, to the connector on the heated oxygen (rear) sensor side.
2. Measure the resistance between heated oxygen sensor connector terminal No. 3 and terminal No. 4.
Standard value: 11 - 18 Ohms [at 20 °C (68 °F)]
Q: Is the measured resistance between 11 and 18 Ohms [at 20 °C (68 °F)]?
YES: Go to Step 3.
NO: Replace the heated oxygen sensor (rear). Then go to Step 12.
STEP 3. Measure the power supply voltage at heated oxygen sensor (rear) harness side connector D-40.
1. Disconnect connector D-40 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 3 and ground.
- Voltage should measure battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) present?
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 No. 4) and heated oxygen sensor (rear) connector D-40 (terminal No. 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. Measure the power supply voltage at ECM connector C-117 by backprobing.
1. Do not disconnect connector C-117.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 54 and ground by backprobing.
- Voltage should measure battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 8.
NO: Go to Step 6.
STEP 6. Check connector C-117 at ECM for damage.
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 D-40 (terminal No. 4) and ECM connector C-117 (terminal No. 54).
Q: Is the harness wire in good condition?
YES: Replace the ECM. Then go to Step 12.
NO: Repair it. Then go to Step 12.
STEP 8. Check connector C-117 at ECM for damage.
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 No. 4) and heated oxygen sensor (rear) connector D-40 (terminal No. 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 D-40 (terminal No. 4) and ECM connector C-117 (terminal No. 54).
Q: Is the harness wire in good condition?
YES: Go to Step 11.
NO: Repair it. Then go to Step 12.
STEP 11. Retest the system.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0141 set?
YES: Replace the ECM. 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. Perform the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0141 set?
YES: Repeat the troubleshooting.
NO: The procedure is complete.