Code No. P0140: Oxygen Sensor (rear) Circuit No Activity Detected

OPERATION

• Refer to Code No. P0137: oxygen sensor (rear) circuit low voltage .
  

FUNCTION

• The oxygen sensor (rear) converts the concentration of oxygen in the exhaust emission into a voltage and inputs the signal to the engine-ECU.
  
• When the air-fuel ratio is richer than the theoretical air-fuel ratio, the oxygen sensor (rear) outputs a voltage of about 1 V. When it is leaner than the theoretical air-fuel ratio, it outputs a voltage of about 0 V.
  
• In response to the signal, the engine-ECU controls the fuel injection amount so that the air-fuel ratio can be equivalent to the theoretical air-fuel ratio.
  

TROUBLE JUDGMENT

• Engine coolant temperature is more than 76°C.
  
• Oxygen sensor (front) is active.
  
• The cumulative air flow sensor output is more than 340 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 %.
  
• Vehicle speed is more than 30 km/h.
  
• 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.
  

• Change in the output voltage of the oxygen sensor (rear) is less than 0.1 V.
  

• The maximum output voltage of the oxygen sensor (rear) is less than 0.02 V.
  

FAIL-SAFE AND BACKUP FUNCTION

• None
  

PROBABLE CAUSES

• Failed oxygen sensor (rear)
  
• Harness damage in oxygen sensor (rear) circuit
  
• Failed engine-ECU
  

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Go to Step 2.

	Check oxygen sensor (rear) system. Check Code No. P0137: oxygen sensor (rear) circuit low voltage (Refer to ). Check Code No. P0138: oxygen sensor (rear) circuit high voltage (Refer to ).

	Check end.