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. 2 of the heated oxygen sensor (rear) is grounded with ECM (terminal No. 75)
- The ECM
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
- Heated oxygen sensor (rear) output voltage does not reach 0.2 volt after fuel cut operation.
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
Sensor (The sensor below is determined to be normal)
- Volume airflow sensor
- Barometric pressure sensor
- Intake air temperature sensor
- Engine coolant temperature sensor
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- Engine coolant temperature is higher than 76 degrees C (169 degrees F).
- The heated oxygen sensor (front) is active.
- The cumulative volume airflow sensor output frequency is higher than 4,000 Hz.
- Fuel is being shut off.
Judgement Criterion
- Heated oxygen sensor (rear) output voltage does not reach 0.2 volt for 6 seconds from fuel cut start.
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 - Pattern 19 OBD-II Drive Cycle Pattern Lists.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Heated oxygen sensor (rear) deteriorated.
- Connector damage.
- 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. Replace the heated oxygen sensor (rear).
1. Replace the heated oxygen sensor (rear).
2. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19 OBD-II Drive Cycle Pattern Lists.
3. Check the diagnostic trouble code (DTC).
Q: Is DTC P0139 set?
YES: Refer to DTC P0137 - Heated Oxygen Sensor Circuit Low Voltage (sensor 2), DTC P0138 - Heated Oxygen Sensor Circuit High Voltage (sensor 2).
NO: The inspection is complete.