Code No. P0133: Oxygen Sensor (front) Circuit Slow Response

OPERATION

• The sensor signal is inputted to the engine-ECU connector terminal O2FL from the oxygen sensor (front) output terminal.
  
• The oxygen sensor (front) connector terminal is earthed with engine-ECU connector terminal OFLE.
  
• The engine-ECU connector terminal OFLE applies an offset voltage of 0.5 V to the oxygen sensor (front) connector terminal.
  

FUNCTION

• The oxygen sensor (front) 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 (front) 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 60°C.
  
• Engine speed is more than 1,500 r/min and is less than 3,500 r/min. <M/T>
  
• Engine speed is more than 1,200 r/min and is less than 3,000 r/min. <CVT>
  
• Volumetric efficiency is more than 18 % and is less than 65 %. <M/T>
  
• Volumetric efficiency is more than 25 % and is less than 65 %. <CVT>
  
• Under the closed loop air/fuel control.
  
• The accelerator pedal is open.
  
• Short-term fuel trim is more than -25 % and is less than +25 %.
  
• More than 2 seconds have elapsed after the above mentioned conditions have been met.
  
• The engine-ECU monitors for this condition for 5 cycles of 10 seconds each during the drive cycle.
  

• The average of the oxygen sensor (front) rich/lean switching frequency is less than 5 times per 10 seconds.
  

FAIL-SAFE AND BACKUP FUNCTION

• None
  

PROBABLE CAUSES

• Failed oxygen sensor (front)
  
• Loose connector contact
  
• 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.

	Go to Step 3.

	Repair or replace the connector, or replace oxygen sensor (front).

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

	Replace the engine-ECU.