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DTC P0140: Heated Oxygen Sensor (rear) Circuit No Activity Detected
 
 
 
 
CIRCUIT OPERATION
  • A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM terminal O2RL from the output terminal of the heated oxygen sensor (rear).
  • Ground terminal of the heated oxygen sensor (rear) is grounded with ECM terminal ORLE.
  • The ECM applies an offset voltage of 0.5 volt to ground terminal of the heated oxygen sensor (rear).
 
 
TECHNICAL DESCRIPTION
  • The output signal of the linear air-fuel ratio sensor is compensated by the output signal of the heated oxygen sensor (rear).
  • The ECM checks for the heated oxygen sensor (rear) output voltage.
 
 
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 stored in memory for the item monitored below)
  • Linear air-fuel ratio sensor monitor
  • Linear air-fuel ratio sensor heater monitor
  • Heated oxygen sensor heater (rear) monitor
  • Heated oxygen sensor offset voltage monitor
Sensor (The sensor below is determined to be normal)
  • Mass 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 more than 76°C (169°F).
  • The linear air-fuel ratio sensor is active.
  • The cumulative mass airflow sensor output is more than 901 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 80 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 12 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Heated oxygen sensor (rear) deteriorated.
  • Connector damage.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tool:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), check data list item AD: Heated Oxygen Sensor (rear).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Start the engine and run at idle.
(3) Set scan tool (M.U.T.-III) to the data reading mode for item AD, Heated Oxygen Sensor (rear).
  1. Transaxle: 2nd (CVT: L range) speed
  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 12 .
(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.