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.

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) sends a voltage of about 1 V. When it is leaner than the theoretical air-fuel ratio, it sends 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


Check Conditions
  • Engine coolant temperature is more than 60°C.
  • Engine speed is more than 1,200 r/min and is less than 3,000 r/min. <4B11>
  • Engine speed is more than 1,100 r/min and is less than 3,000 r/min. <4B12>
  • Volumetric efficiency is more than 27 % and is less than 65 %. <4B11>
  • Volumetric efficiency is more than 18 % and is less than 60 %. <4B12>
  • 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 7 cycles of 10 seconds each during the drive cycle.
Judgement Criterion
  • The average of the oxygen sensor (front) rich/lean switching frequency is less than 6 times per 10 seconds.

FAIL-SAFE AND BACKUP FUNCTION



  • None

PROBABLE CAUSES



  • Failed oxygen sensor (front)
  • Loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

  • Data list reference table (Refer to ).

  1. Item AC: Oxygen sensor (front)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2.

STEP 2. Check oxygen sensor (front) itself.



  • Oxygen sensor (front) check (Refer to ).

Q. Is the check result normal?
Go to Step 3.
Replace oxygen sensor (front).

STEP 3. Connector check: oxygen sensor (front) connector and engine-ECU connector

Q. Are the check results normal?
Go to Step 4.
Repair or replace the connector.

STEP 4. M.U.T.-III data list

  • Data list reference table (Refer to ).

  1. Item AC: Oxygen sensor (front)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.