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CHAPTER 5 OXYGEN SENSOR TESTING PAGES 1 3

Topics covered

  • O2 sensor signal circuit testing
  • normal operating voltage and frequency range of an O2 signal
  • why scan data cannot show you O2 frequency
  • what is O2 switch time
  • voltage over time vs voltage over frame
  • scan data graph of an O2 can be misleading
  • why a digital voltmeter will average an O2 signal
  • slow response O2 codes
  • identifying sensor side wiring colors
  • identifying sensor locations
  • how to test an O2 heater circuit using scan data
 

CHAPTER 5 OXYGEN SENSOR TESTING PAGES 4 7

Topics covered

  • using a downstream O2 to confirm upstream O2 signals
  • O2 signal fixed rich or lean troubleshooting
  • is the O2 sensor lying?
  • using tailpipe emissions to determine sensor accuracy
  • adding propane, creating vacuum leaks to check O2 response
  • five gas theory (tailpipe emissions)
  • which tailpipe gas is your rich and lean indicator
  • causes of positive and negative fuel trim numbers
  • heater circuit power and ground test
  • what a lean misfire looks like at the tailpipe
  • false lean compared to actual lean conditions
 

CHAPTER 5 OXYGEN SENSOR TESTING PAGES 4 11

Topics covered

  • actual rich and lean, false lean condition, intro to bias
  • jumped timing chain causing a rich condition case study
  • HC and CO tailpipe emissions
  • AIR system false lean
  • O2 sensor fixed voltage variables
  • using bias voltage and a scan tool to test for open or shorted signal circuit
  • checking bias voltage with a voltmeter
  • PCM response test
 

CHAPTER 5 OXYGEN SENSOR TESTING PAGES 11 13 23

O2 sensor bias voltage is a difficult subject to talk about but easy to use in the field. We will be able to use this bias voltage to quickly and accurately test for opens and shorts in the O2 signal circuit as well as determine O2 heater circuit function. Included in this lecture is no bias voltage circuit testing.

Topics covered

  • resistance of a cold oxygen sensor
  • why bias voltage drops as the sensor warms up
  • voltmeter effects on bias voltage
  • using bias voltage to test the heater circuit
  • Oharness side/sensor side colors 16:03
  • fixed signal testing
  • measuring bias voltage with a voltmeter and scan data
  • using bias voltage to verify circuit integrity
  • signal circuit testing with no bias voltage (Ford) 26
  • identifying O2 location without knowing where #1 cyl. is
  • O2 PCM response test (without scan data)
  • simulating rich/lean signals (voltage levels applied) 45:20
 

CHAPTER 5 OXYGEN SENSOR TESTING NO BIAS TESTS USING BIAS FOR HEATER ACTIVITY

In this lecture, we will cover bypassing the O2 sensor signal both with a test light connected to battery positive and using our bodies as a resistor. Also O2 sensor heater circuit quick tests using bias voltage is discussed.

Topics covered

  • a fixed O2 signal may cause the PCM to use fuel trim from the other bank
  • how to reset the keep alive memory
  • adding propane to verify O2 response 5:40
  • verify signal circuit integrity with test light or finger
  • voltage/current being applied through your body 8:40
  • voltage/current being applied through your test light
  • Chrysler bias voltage
  • effects of inactive heater circuit 18:40
  • time to activity test
 

CHAPTER 5 OXYGEN SENSOR TESTING PAGES 14 22 FINISH SIGNAL BIAS GROUND BIAS HEATER CIRCUITS

In this video I finish our discussion of signal circuit bias and review ground circuit bias voltage as well as heater circuit controls and testing.

Topics covered

  • purpose of bias voltage on signal wire
  • using bias voltage to diagnose stuck high and low signal voltage
  • heater circuit checks
  • purpose of sensor ground bias voltage 16:30
  • when to use sensor ground over battery negative
  • global data vs OEM data
  • O2 heater control designs (pulse width modulation)
  • when to use OEM sensors
 

CHAPTER 5 OXYGEN SENSOR TESTING PAGES 19 27 EXPANDED CONTENT

In this final video of my chapter 5 material I am using one of my older lectures reviewing heater circuit testing, PCM response testing and catalytic converter oxygen storage. Some of this is repeat material but the two O2 heater circuit case studies discussed and the oxygen storage test of the cat makes this a must watch video to finish up this chapter.

Topics covered

  • oxygen sensor heater circuit testing
  • average reading of a voltmeter on a PWM heater circuit
  • testing a non PWM heater circuit
  • identifying O2 wiring based on voltage measurements
  • testing heater circuit current
  • open heater case study on a Honda 18:35
  • intentional shut-down of a heater circuit
  • open heater case study on a Lexus (bad computer?) 22:20
  • importance of measuring current flow on heater circuits
  • PCM response testing 29:25
  • catalytic converter oxygen storage 37:49
 

2007 NISSAN SENTRA O2 HEATER CIRCUIT OPERATION AND TESTING P1148 P0031

This is a classroom lecture, case study combination created to emphasize how to test an O2 sensor heater circuit with a fault. We will be using pages from my book as well as live testing on a car in my classroom.

Topics covered

  • O2 heater controls
  • pulse width modulation, duty cycle controls and frequency measurements
  • ground side switched circuits (circuit ID, causes of low voltage on a G.S.S. control wire)
  • how to test a transistor driver with a test light
  • scan data commands compared to actual control
  • open circuit ohm test.
 
 

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