P0155
DTC P0155: Heated Oxygen Sensor Heater Circuit (bank 2, sensor 1)Left Bank Heated Oxygen Sensor (front) Heater Circuit Part 1:
Left Bank Heated Oxygen Sensor (front) Heater Circuit Part 2:
CIRCUIT OPERATION
- Power is supplied from the MFI relay (terminal No. 4) to the left bank heated oxygen sensor (front) heater.
- The ECM (terminal No. 3)
TECHNICAL DESCRIPTION
- The ECM
DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor heater (front) 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 left bank heated oxygen sensor (front) heater is on.
- Battery positive voltage is at between 11 and 16.5 volts.
Judgment Criteria
- Heater current of the left bank heated oxygen sensor (front) heater has continued to be lower than 0.16 ampere or higher than 7.5 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 left bank heated oxygen sensor (front) heater circuit harness damage.
- Open circuit in left bank heated oxygen sensor (front) heater.
- ECM failed.
- PCM failed.
- Connector damage.
DIAGNOSIS
Required Special Tool:
- MB998464: Test Harness
STEP 1. Check connector B-24 at the left bank heated oxygen sensor (front) for damage.
Q: Is the harness 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 left bank heated oxygen sensor (front).
1. Disconnect left bank heated oxygen sensor (front) connector B-24 and connect test harness special tool, MD998464, to the connector on the left bank heated oxygen (front) sensor side.
2. Measure the resistance between heated oxygen sensor connector terminal 1 (red clip) and terminal 3 (blue clip).
Standard value: 4.5 - 8.0 Ohms [at 20 °C (68 °F)]
Q: Is the measured resistance between 4.5 and 8.0 Ohms ?
YES: Go to Step 3.
NO: Replace the left bank heated oxygen sensor (front). Then go to Step 12.
STEP 3. Check the power supply voltage at left bank heated oxygen sensor (front) harness side connector B-24.
1. Disconnect the connector B-24 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 1 and ground.
- Voltage should be 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 connector A-18X at the MFI relay for damage.
Q: Is the connector in good condition?
YES: Repair harness wire between MFI relay connector A-18X (terminal No. 4) and left bank heated oxygen sensor (front) connector B-24 (terminal No. 1) 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-51
1. Do not disconnect the connector C-51
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 3 and ground by backprobing.
- Voltage should be 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-51 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 or short circuit to ground between left bank heated oxygen sensor (front) connector B-24 (terminal No. 3) and ECM connector C-51 (terminal No. 3)
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-51 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 A-18X (terminal No. 4) and left bank heated oxygen sensor (front) connector B-24 (terminal No. 1).
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 left bank heated oxygen sensor (front) connector B-24 (terminal No. 3) and ECM connector C-51 (terminal No. 3)
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 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 P0155 set?
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 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 P0155 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.