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.

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1. (a) Connect the Techstream to the DLC3.
2. (b) Start the engine and warm it up with all the accessories switched OFF until the engine coolant temperature stabilizes.
3. (c) Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes.
4. (d) While running the engine at 3000 rpm and 2000 rpm at 2 second intervals, check the waveforms of the A/F and HO2 sensors using the Techstream.

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 the 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).

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002