Conditioning For Sensor Testing

HINT:

Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.

1. Connect Techstream to the DLC3.
2. Start the engine and warm it up with all the accessories switched OFF, until the engine coolant temperature stabilizes.
3. Run the engine at an engine speed of between 2,500 rpm and 3,000 rpm for at least 3 minutes.
4. While running the engine at 3,000 rpm and 2,000 rpm alternating at 2 second intervals, check the waveforms of the A/F and HO2 sensors using the tester.

   HINT:

   • If either voltage output of the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not fluctuate, or there is a noise in the waveform of either sensor, the sensor may be malfunctioning.
   • If the voltage outputs of both the sensors remain lean or rich, the air-fuel ratio may be extremely lean or rich. In such cases, perform the following Control the Injection Volume for A/F Sensor using Techstream.
   • If the Three-Way Catalytic Converter (TWC) has deteriorated, the HO2 sensor (located behind the TWC) voltage output fluctuates up and down frequently, even under normal driving conditions (active air-fuel ratio control is not performed).
     Fig 2: A/F Sensor And HO2 Sensor Waveform Graph

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