Скачать или смотреть Weekly Waveform 21 - Testing Oxygen Sensor Signal and Heater Circuits

In the automotive weekly waveform #21 I will show you how to scope a narrow band O2 sensor circuit. I will be scoping the rear O2 sensor signal and heater circuit on my 2004 Chevrolet express van with a 5.3.

The heater circuit on this van gets power anytime the key is on and the computer controls the ground circuit. If the heater doesn't work properly the oxygen sensor will take a long time to warm up and the tailpipe emissions will be higher.

The signal circuit will fluctuate between 0.1 volt and 0.9 volt on a good sensor. If checking a front O2 sensor the signal will switch from high to low at least once per second. The rear O2 will have a much slower switch interval if the vehicle has a good catalytic convertor. Many rear O2 sensor will hover between 650mv and 850mv most of the time if the convertor is good.

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