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DTC P0140: Heated Oxygen Sensor (rear) Circuit No Activity Detected
 
 
 
 
CIRCUIT OPERATION
Refer to DTC P0137 - Heated Oxygen Sensor (rear) Circuit Low Voltage .
 
 
TECHNICAL DESCRIPTION
  • The heated oxygen sensor (rear) converts the concentration of oxygen in the exhaust emission into a voltage and inputs the signal to the ECM.
  • When the linear air-fuel ratio is richer than the theoretical linear air-fuel ratio, the heated oxygen sensor (rear) outputs a voltage of about 1 volt. When it is leaner than the theoretical linear air-fuel ratio, it outputs a voltage of about 0 volt.
  • In response to the signal, the ECM controls the fuel injection amount so that the linear air-fuel ratio can be equivalent to the theoretical linear air-fuel ratio.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • 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 set in memory for the item monitored below)
  • Linear air-fuel ratio sensor heater monitor
  • Heated oxygen sensor (rear) heater monitor
  • Heated oxygen sensor offset voltage monitor
Sensor (The sensor below is determined to be normal)
  • Linear air-fuel ratio sensor
  • Mass airflow sensor
  • Engine coolant temperature sensor
  • Intake air temperature sensor 1
  • Barometric pressure sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Conditions
  • Engine coolant temperature is more than 76°C (169°F).
  • The linear air-fuel ratio sensor is active.
  • The cumulative mass airflow sensor output is more than 1,638 g.
  • Repeat 1 time or more: drive*1, stop*2.
    • Drive*1:
      • Engine speed is more than 1,500 r/min.
      • Volumetric efficiency is more than 40 percent.
      • Vehicle speed is more than 30 km/h (19 mph).
      • A total of more than 60 seconds have passed with the above mentioned conditions, and more than 3 seconds have passed with the fuel shut off.
    • Stop*2:
      • Vehicle speed is less than 1.5 km/h (1 mph).
Judgment Criterion
  • Change in the output voltage of the heated oxygen sensor (rear) is less than 0.313 volt.
or
  • The maximum output voltage of the heated oxygen sensor (rear) is less than 0.508 volt.
noteMonitoring stops after fuel has been shut off for more than 64 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 17 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Heated oxygen sensor (rear) failed.
  • Harness damage in heated oxygen sensor (rear) circuit.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), check data list item AD: Heated Oxygen Sensor (rear).
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Start the engine and run at idle.
(3) Set scan tool (M.U.T.-IIISE) to the data reading mode for item AD, Heated Oxygen Sensor (rear).
  1. Transaxle: 2nd
  2. Drive with wide open throttle
  3. Engine: 3,500 r/min or more
    • The output voltages should be between 0.6 and 1.0 volt.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
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 - Pattern 17 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0140 set?
Refer to DTC P0137 - Heated Oxygen Sensor (rear) Circuit Low Voltage , DTC P0138 - Heated Oxygen Sensor (rear) Circuit High Voltage .
The inspection is complete.