Conditioning For Sensor Testing

HINT:

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

Fig 1: Engine Speed Graph

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1. Connect the 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 2500 rpm and 3000 rpm for at least 3 minutes.
4. While running the engine at 3000 rpm for 2 seconds and 2000 rpm for 2 seconds, check the waveforms of the A/F and HO2 sensors using the tester.

   HINT:

   • If either of the voltage outputs of the A/F or HO2 sensor does not fluctuate, or either of the sensors makes a noise, 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 menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
   • 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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