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Check the signal voltage of the oxygen sensor

Date:Aug 16, 2019

1. With the ignition switch turned off, disconnect the 4-pin connector on the oxygen sensor.

2. The 12V power supply of the battery is led to the resistance heating end of the oxygen sensor. This method requires a pair of wire connectors, that is, test fixtures. After starting, start the engine and measure the voltage at the signal output after 2 minutes.


If you think that the operability of this method is not strong, you can start the engine directly. After 2 minutes, unplug the four-core connector and quickly measure the voltage at the signal end of the oxygen sensor. (After the heating resistor is removed from the power supply, the core of the oxygen sensor will cool and the measurement error will increase) (I used the second one)


Under the idle state after starting the engine, according to the above working principle, the output voltage should be very low; then the throttle is increased, and at the moment of the throttle change, there will be a voltage output, which is related to the rate of change of the throttle (ie, the throttle is stabilized) The voltage disappears instantly. The faster the voltage, the higher the voltage. The maximum value is up to 0.9V. If it is a pointer meter, this voltage can only read 0.8V due to inertia and damping factors. (Considering the response time of the digital meter, it cannot be measured with a digital meter, otherwise the error is very large)


If the oxygen sensor has no voltage output, the voltage value is constant, the voltage rises or falls very little, and the voltage changes slowly, it indicates that there is a problem with the sensing element of the oxygen sensor. In this case, consider cleaning the oxygen sensor.

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