Oxygen sensor: signs of malfunction. What is a lambda probe (oxygen sensor)?

From the article you will learn about what an oxygen sensor is. Symptoms of a malfunction of this device will make you think about replacing it. Because the first sign is a significant increase in the consumption of gasoline. The reasons for this behavior will be described below. And first you need to talk a little about the history of creating this device, as well as its operating principles.

The need for an oxygen sensor

And now about what an oxygen sensor is needed for in the car. Symptoms of its malfunction will be considered later. When you burn any fuel you need access to oxygen. Without this gas, the combustion process can not take place. Consequently, oxygen must necessarily enter the combustion chambers. As you know, the fuel mixture is a mix of gasoline and air. If you pour clean gasoline into the combustion chambers, the engine simply will not work. By how much oxygen remains in the exhaust system, we can say how well the fuel-air mixture burns in the cylinders of the engine. It is for measuring the amount of oxygen that a lambda probe is needed.

A bit of history

At the end of the 1960s, for the first time, automakers began to try to install these sensors on machines. The very first oxygen sensors were installed on Volvo cars. An oxygen sensor is also called a lambda probe. The fact is that there is a letter "lambda" in the Greek alphabet. And if you look at the reference literature on internal combustion engines, you can see that it is this letter that indicates the coefficient of excess air in the fuel mixture. And this parameter allows to measure the oxygen sensor (lambda probe).

Principle of operation

An oxygen sensor is installed exclusively on injection vehicles using electronic engine control units. The signal generated by it is fed to the control unit. This signal is used by the microcontroller in order to make the correct adjustment of the mixture formation. It adjusts the air supply to the combustion chambers. Of course, the quality of the mixture is affected not only by the signal coming from the oxygen sensor, but also from most other devices that can measure the load on the engine, its speed, as well as the speed of the car, and so on. Often in cars, two lambda probes are installed. One is working, and the other is for adjustment. They are installed before the catcollector and after. Note that the lambda probe, which is mounted after the catcollector, has an additional forced heating. Before you clean the oxygen sensor, be sure to read the requirements that are set by its manufacturer.

Lambda probe operating conditions

Also it should be taken into account that the most efficient functioning of this sensor occurs at temperatures from 300 degrees and above. It is for this purpose that an electric heater is needed. It allows to maintain the normal functioning of the oxygen sensor in the mode of the unheated engine. The sensor element of the sensor must be located directly in the exhaust gas flow. So that its electrode, located on the outside, must be washed by a stream. The internal electrode must be placed directly in the atmospheric air. Of course, the oxygen content is different. And between these two electrodes, a certain potential difference begins to form. The output voltage may appear at a maximum of 1 volt. It is this voltage that is fed to the electronic control unit. He, in turn, analyzes his signal, then, according to the fuel card embedded in it, increases or decreases the opening time of the injectors, changes the air supply to the ramp.

Broadband

There is such a device as a broadband oxygen sensor. The signs of a malfunction (UAZ "Patriot" has the same as any other car) sensors consist in the fact that the operating mode of the engine changes. The difference between the usual and such a device is quite large. The fact is that they have very different principles of functioning and sensitive parts. A broadband lambda probes are more informative, and this is true for cases if the engine is operating in non-standard modes. Therefore, the richer the information, the more precise the settings will be made by the electronic control unit.

How to identify a breakdown

It is worth noting that the oxygen sensors affect the functioning of the motor very much. If suddenly the lambda probe orders to live for a long time, then the engine most likely will not work. When a lambda probe breaks down, there is no signal output, or it changes in an unpredictable manner. Of course, this behavior will greatly complicate your daily life. The sensor can go out of order literally at any minute. For this reason, there are certain functions on the cars that allow the engine to start and also reach the service station even if the oxygen sensor is defective.

Emergency Firmware

The fact is that when the electronic control unit sees a damage to the lambda probe, it starts to work not according to the firmware installed in it by default, but by the emergency one. In this case, the mixture formation takes place according to data obtained from other sensors. Only the oxygen sensor is not involved in this process. The driver will notice the signs of a malfunction of this device immediately. Unfortunately, the mixture is too poor, since the percentage of gasoline is more than necessary. This allows you to ensure that the engine does not stop. But if you increase the air supply, then the chances are that the engine stalls. However, as a warning on most cars, the Check Engine lamp lights up in the instrument panel, which signals engine malfunctions. The literal translation of this inscription is "Check the engine". But even without it you can determine the breakdown of the lambda probe. The fact is that fuel consumption is growing strongly in comparison with the normal regime.

Conclusion

Now you know what an oxygen sensor (lambda probe) is, what are its properties and features. In conclusion, I would like to mention that this element is very demanding on how it is installed. Pay attention to the fact that there are no slots between the sensor housing and the catcollector, otherwise it will lead to premature failure of the device. In addition, during operation the sensor will send incorrect information to the control unit.