P0139
Right Bank Heated Oxygen Sensor (rear) Circuit:
Connectors:
DTC P0139: Heated Oxygen Sensor Circuit Slow Response (bank 1, sensor 2)
CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 74)
- Terminal No. 2 of the right bank heated oxygen sensor (rear) is grounded with ECM (terminal No. 49)
TECHNICAL DESCRIPTION
- The output signal of the right bank heated oxygen sensor (front) is compensated by the output signal of the right bank heated oxygen sensor (rear).
- The ECM
DESCRIPTIONS OF MONITOR METHODS
Right bank heated oxygen sensor (rear) output voltage does not change during specified go/stop operations including fuel cut are repeated.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Heated oxygen sensor heater (front) monitor
- Heated oxygen sensor heater (rear) monitor
- Air/fuel ratio feedback monitor
Sensor (The sensor below is determined to be normal)
- Volume airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor
DTC SET CONDITIONS
Logic Flow Chart:
Check Conditions
- Engine coolant temperature is higher than 76° C (169° F).
- The right bank heated oxygen sensor (front) is active.
- The cumulative volume airflow sensor output frequency is higher than 4,000 Hz.
- Repeat 3 or more times: drive*1, stop*2.
Drive*1:
- Engine speed is higher than 1,500 r/min.
- Volumetric efficiency is higher than 40 percent.
- Vehicle speed is higher than 30 km/h (19 mph).
- A total of more than 10 seconds have elapsed with the above mentioned conditions, and more than 2 seconds have elapsed with the fuel shut off.
Stop*2:
- Vehicle speed is lower than 1.5 km/h (1.0 mph).
Judgement Criteria
- Change in the output voltage of the right bank heated oxygen sensor (rear) is lower than 0.312 volt.
NOTE: Monitoring stops after fuel has been shut off for more than 38 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 4 - Heated Oxygen Sensor Monitor.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Right bank heated oxygen sensor (rear) failed.
- Connector damage.
- PCM failed.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991502: Scan Tool (MUT-II)
- MB991316: Test Harness
STEP 1. Using scan tool MB991502, check data list item 69: Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991502 to the data reading mode for item 69, Heated Oxygen Sensor Bank 1, Sensor 2 (right rear).
4. Warm up the engine.
- After increasing the output voltage 0.15 volt or more by the engine revving, finish it. Then confirm that the output voltage reduces to 0.15 volt or less within 3 seconds.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: It can be assumed that this malfunction is intermittent. Refer to INTRODUCTION, How to Use Troubleshooting/Inspection Service Points How to Cope with Intermittent Malfunctions.
NO: Replace the heated oxygen sensor (rear). Then go to Step 2.
STEP 2. Check the right bank heated oxygen sensor (rear).
1. Disconnect the right bank heated oxygen sensor (rear) connector B-28 and connect test harness special tool, MB991316, to the connector on the right bank heated oxygen sensor (rear) side.
2. Warm up the engine until engine coolant temperature reaches 80° C (176° F) or higher.
3. Perform a racing for 5 minutes or more with the engine speed of 4,500 r/min.
4. Connect a digital voltage meter between terminal No. 2 (black clip) and terminal No. 4 (white clip).
5. While repeatedly revving the engine, measure the right bank heated oxygen sensor (rear) output voltage.
Standard value: 0.6 - 1.0 volt
CAUTION:
- Be very careful when connecting the jumper wire; incorrect connection can damage the right bank heated oxygen sensor.
- Be careful the heater is broken when voltage of beyond 12 volts is applied to the right bank heated oxygen sensor heater.
NOTE: If the sufficiently high temperature [of approximate 400° C (752° F) or more] is not reached although the right bank heated oxygen sensor is normal, the output voltage would be possibly low although the rich air/fuel ratio. Therefore, if the output voltage is low, use a jumper wire to connect the terminal No.1 (red clip) and the terminal No.3 (blue clip) of the right bank heated oxygen sensor with the positive terminal and the negative terminal of 12 volts power supply respectively, then check again.
Q: Is the measured voltage between 0.6 and 1.0 volt?
YES: Go to Step 3.
NO: Replace the right bank heated oxygen sensor (rear). Then go to Step 4.
STEP 3. Check harness connector B-28 at right bank heated oxygen sensor (rear) and harness connector C-118, C-122 at ECM or C-115, C-119 at PCM for damage.
Q: Is the harness connector in good condition?
YES: Replace the ECM or PCM. Then go to Step 4.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 4.
STEP 4. 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 4 - Heated Oxygen Sensor Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0139 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.