Hello Friends
Just Want To Share One Small Yet Important Stuff With You Guys.........!
Was Thinking Of Trying It From Decades And Finally I Did It....
Its A Testing Of O2 Sensor Working.........The Sensor I tested Was Denso 4 Wire Heater Type O2 Sensor......
1st Check The Resistance Between Both heater Terminals And It Should Measure Around Around 11-15Ohms.....!
Its Important To Check Heater For Sensors Proper Functioning....A Busted Heater Circuit With Working Sensor Is Useless Also....It Will Not Maintain Temperatures Required To Make O2 Function Properly......
Coming Towards Sensor Check So In 4 Wire O2 Sensor...The Wires Goes Like
Black------Heater +ve
Black------Heater -ve(HT On ECU) Toyota Pinout
Blue-------Signal Wire To ECU
White-----Ground Wire
This Is Typical Color Combination of Most Of Denso Sensors.....Some Have Different Color Codes But Wiring Remain same
What We DO Now Is Connect Ground Probe Of Multi-meter With Negative Of Sensor And +ve Probe To Signal Wire On o2 Sensor ......And Measure DC Voltage....
Now Using Grip Plier Or Plier...Hold O2 Sensor From Its Socket Side And Light Up Small Flame.....I Used A Regulator To Make It Safe And Low......Don't Use High Flame All At Once As It Can Damage Your Sensor.....A Small SLOW Flame Is Way To Go.....
A Proper Working Sensor Will Start Raising Voltage From 0 To Maxx 0.9v As It Gets Heated.......Then Once You Remove From Flame....It Will Instantly Drop Voltages As Can Be Seen In Pics...Then Put It Again On Flame And It Will Increase Voltages......!!
If The Voltage Don't Raise Like That Or Stuck At One Place And Don't Change Too Often...It Means Sensor Is Busted or Almost End Of Its Life.....!! It Should Revert Back And Shoot Up Within 4 Second Mark.....!
This Way You Can Check Your O2 Sensors If You Don't Have Any Scanner Or Tool......
The 1 Wire 2 Wire Sensor Can be Checked In Similar Way....1 Wire Sensor Have Signal Wire And Sensor Body As Ground
In 2 wire...One Is Signal And Other Is Sensor Ground.......!
3 Wire Sensors Also Have Same Where 2 Are Heater Wires 1 Is Signal And The Sensor Is Grounded....But Mostly 4 wire O2 Sensor Is Common Along With AFR Sensor Whose voltage Reading Are Wide And See More Better Mixtures
Hope It Helps
Regards