Conditioning A/F Sensor And Heated Oxygen Sensor For Testing

Fig 1: Conditioning A/F Sensor And Heated Oxygen Sensor For Testing

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Connect the OBD II scan tool or the hand-held tester to the DLC3.
Put the engine in inspection mode (See PRECAUTION ).
Start the engine and warm it up with all the accessories switched OFF until the engine coolant temperature becomes table.
Run the engine at 2,500 RPM for approximately 3 minutes.
Run the engine at 2,500 RPM for 2 seconds and then 1,500 RPM for 2 seconds
Check the waveform of the oxygen sensor (sensor 2).

HINT:

If output of the A/F sensor or the heated oxygen sensor does not fluctuate or has noise, the sensor may be malfunctioning.

If voltage output of both sensors remain at LEAN or RICH, the air-fuel ratio may be extremely LEAN or RICH. In such a case, perform the following A/F CONTROL operation in ACTIVE TEST using the hand-held tester. If the catalyst has deteriorated, the voltage output of the heated oxygen sensor fluctuates up and down widely even under normal driving ("active air-fuel ratio control" is not performed).

Fig 2: Heated Oxygen Sensor Voltage Output Graph