In this video I’ll show how to perform an oxygen sensor response test, and how to inspect for a leaking fuel pressure regulator. The oxygen sensor response test demonstrated can be successfully applied to any oxygen or air/fuel ratio sensor, regardless of design or number of wires. This test is extremely valuable when diagnosing fuel trim issues, when the accuracy of the oxygen sensor is in question.

Engine Performance Diagnostics chapter 5 page 4, and chapter 14 page 9

symptoms 50

  • intermittent rough idle
  • intermittent stalling
  • long/extended cranking time
  • start/stall
  • poor gas mileage

fix 50

  • replace leaking fuel pressure regulator

test shown enh 50

  • using scan data to monitor fuel trims
  • interpreting short and long term trims
  • performing an O2 response test
  • how to test for a leaking fuel pressure regulator

Tools used

  • scan tool

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

Related videos:

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


How to identify a bad oxygen sensor (signal fixed rich):


System Too Rich P0172, P0175 from a blown O2 heater fuse (Jeep):


How to simulate a rich & lean O2 signal (PCM response testing):


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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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