How to measure an O2 sensor signal with a scope and multimeter.

The car being tested in this video is a Honda but you can follow the procedures shown for any 4-wire heated oxygen sensor.

You do not need a scope to do these tests, you can follow along with your digital multimeter.

Engine Performance Diagnostics chapter 5 pages 2-3

test shown enh 50

  • signal circuit tests (amplitude and frequency)
  • heater circuit tests
  • signal circuit integrity testing
  • scope testing an oxygen sensor
  • digital voltmeter tests

Tools used

  • lab scope
  • digital multimeter
  • back-probing tool

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(Chapters 4 and 5) Fuel Trim and Oxygen Sensor Testing

Related videos:

Ford O2 Sensor wiring quick tests (no bias voltage):


It's back! But is it the same problem? (1988 F-150):


Fixed rich O2, low power, misfire (Mitsubishi Eclipse):


Chevy 4.8 Oxygen Sensor Test (fixed rich signal P0172, P0175):


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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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