P0139
DTC P0139: Heated Oxygen Sensor Circuit Slow Response (sensor 2)Heated Oxygen Sensor (rear) Circuit Part 1:
Heated Oxygen Sensor (rear) Circuit Part 2:
CIRCUIT OPERATION
- A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 75)
- Terminal No. 2 of the heated oxygen sensor (rear) is grounded with ECM (terminal No. 92)
TECHNICAL DESCRIPTION
- The output signal of the heated oxygen sensor (front) is compensated by the output signal of the heated oxygen sensor (rear).
- The ECM
DESCRIPTIONS OF MONITOR METHODS
- If the heated oxygen sensor (rear) output does not change in spite of repeating the prescribed (stop-and-go) driving pattern that includes a fuel shut-off, the heated oxygen sensor (rear) is determined to be stuck with faulty output.
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 (front) heater monitor
- Heated oxygen sensor (rear) heater monitor
- Air fuel ratio feedback system monitor
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow chart
Sensor (The sensor below is determined to be normal)
- Volume airflow sensor
- Barometric pressure sensor
- Intake air temperature sensor
- Engine coolant temperature sensor
Check Conditions
- Engine coolant temperature is higher than 76 °C (169 °F).
- The 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 (18.7 mph).
- A total of more than 10 seconds have elapsed with the 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 (0.9 mph).
Judgement Criteria
- Change in the output voltage of the heated oxygen sensor (rear) is lower than 0.313 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. OBD-II Drive Cycle Pattern Lists
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Heated oxygen sensor (rear) failed.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
STEP 1. Using scan tool MB991958, check data list item 59: Heated Oxygen Sensor (rear).
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991958 to the data reading mode for item 59, Heated Oxygen Sensor (rear).
4. Warm up the engine.
- Warm up the engine. When the engine is revved, the output voltage should repeat 0 volt and 0.6 to 1.0 volt alternately.
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 How to Use Troubleshooting/Inspection Service Points.
NO: Replace the heated oxygen sensor (rear). Then go to Step 2.
STEP 2. 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. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0139 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.