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How works the lambda probe interface on a car

Discussion in 'Sensors and Actuators' started by voiture8, Mar 14, 2021.

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  1. voiture8


    Mar 14, 2021
    Hey guys,

    I have a worry with my car when I accelerate, a lost of power. My oxygen sensor was broken, so I changed it but the new I changed has broken too when I started the car (I tested before and it worked well before I installed it on the car). So I read the voltages and I found a difference of voltage. I have a variation in the voltages between the ground_wire and the ground_of_the_car, from 0 to 3V sometimes. I tested the ground on the ECU and the bolts were not tight correctly but even after that there was a variation in the voltages. After, I found a lot old grease around the main connector of the ECU inside the motor part, so I cleaned it and after that the voltages are fixed now. The sensors have 4 wires, I measured the voltages of the signal/ground not the heater part.

    Note the voltages are from the motor not from the sensors, and the sensors are not connected to the motor:

    Sensor 1 (before the catalytic):
    Signal_wire/ground_wire : +0.3V
    Signal_wire/ground_of_the_car: +2.16V
    Ground_wire/ground_of_the_car: +1.85 V

    Sensor 2 (after the catalytic):
    Signal_wire/ground_wire : +0.3V
    Signal_wire/ground_of_the_car: +0.3V
    Ground_wire/ground_of_the_car: 0 V

    Note, the sensor1 is broken and with a ohmmeter I measured an infinite resistance between the ground_wire and the mass_of_the_sensor, in the contrary the sensor2 is working and the resistance of the sensor2 is 0 Ohm.I think it is not good to do that because it could hurt the sensor but I tried because the sensor1 is broken and I think I will change the sensor2 too.

    Why there is a 0.3V between the 2 wires ? That voltage is not dangerous for the sensor. I'm afraid to place another one and lost 100$.

    Why the sensor1 has a difference of potential of 1.85V between the mass of the car and the mass of the wire ? It is because the sensor1 is broken because the small amount of metal is fused ?

    Is the variation of the voltage between the mass can destroy the sensor ?

    Note, my car is a Subaru Impreza, 1.5R, 2007.

    I found 2 schematics, one it shows the voltage 1.8V and the other shows the biais voltage of 0.3V I don't know if it is the reason of the presence of the voltages I found.

    Attached Files:

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    • g5.png
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    Last edited: Mar 14, 2021
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