This article will talk about what a lambda probe is; we will also consider signs of a malfunction of this node. It is also called an oxygen sensor. It is installed in the exhaust tract of an automobile internal combustion engine. Moreover, this sensor is installed both on gasoline and diesel engines.
Oxygen Sensor Basics
The lambda probe is similar in principle to a galvanic cell consisting of a solid ceramic electrolyte based on zirconium. Ceramics were also alloyed with yttrium oxide. Above is a thin layer spraying using platinum. It turns out that one electrode perceives the exhaust gas, while the other - air from the atmosphere. It is due to this that the parameters of the working gas are compared with normal atmospheric air. It is also worth noting that the most effective work is carried out at temperatures above 300 degrees. It is with such heating that the zirconium electrolyte begins to conduct current. And now it's time to find out what affects how the lambda probe works. Signs of a malfunction of Priora, for example, can be determined even by ear.
The principle of operation of the lambda probe
Due to the fact that there is a difference in the mass content of oxygen, an output voltage appears on the electrodes of the sensor. To increase the sensitivity of the device at low temperatures, for example during engine start, it is necessary to use forced heating. The electric coil is located in the ceramic body of the lambda probe. It has a connection to the car's on-board network. There is also an oxygen sensor element based on titanium dioxide. It changes its resistance when the engine is running. It is by this principle that the lambda probe works. Symptoms of the VW Golf 3 are the same as in domestic cars.
Oxygen Sensor Operation
At the moment when the engine starts and warms up, the engine operates without data coming from the lambda probe. All correction of the air-fuel mixture occurs according to data obtained from other devices. In particular, these are sensors for damper position in the throttle, engine temperature, crankshaft speed. The main feature of the zirconium-based lambda probe is that, with a slight deviation from the oxygen content, a significant change in the output voltage occurs in the range 0.1–0.9 volts when analyzing the composition of the fuel mixture.
Titanium oxygen sensors
Sensors made of titanium dioxide are also available. Then, when there is a change in the mass fraction of oxygen in the exhaust gases, they gradually change the resistance in volume. Voltage generation for sensors of this design does not occur. They are much more complicated than zirconium ones, they are used on very expensive cars, for example BMW, Nissan, Jaguar. On budget cars, devices based on titanium, as a rule, are not used, since they have a high cost. On cars of middle and low class cheaper zirconium used lambda probe. Symptoms Renault Megane 2 shows those that are no different from those present on domestic cars.
Differences lambda probes
It is worth noting that the principles of operation for oxygen sensors are the same, do not depend on who the manufacturer is. The only difference is the size of the body of these elements. There may also be a slightly different connection, often there is a difference in the connector. All sensors, as mentioned above, are heated or not. Therefore, they differ in the number of wires to connect. According to materials, the differences are as follows: either zirconium or titanium. In the latter, the output of the heater is always red. There are also types for diesel engines. They are more broadband. You cannot install such a lambda probe on a gasoline engine. Symptoms (Skoda Octavia is also of interest to many motorists) are accompanied by an error code with a brief description.
Why the lambda probe fails
Very often, the cause of premature failure is the poor quality of gasoline. Iron and lead, which may be present in bad gasoline, instantly clog the platinum electrodes. Therefore, the oxygen sensor fails, it cannot normally take all readings. If the oil scraper rings have a strong output, then a certain amount of oil will enter the exhaust pipe . It also causes premature failure of the oxygen sensor. Even if a little solvent or detergent accidentally gets onto the oxygen sensor, you can immediately say that it has broken. He does not survive the ingress of such solutions. The destruction of the lambda probe occurs when claps occur in the exhaust system. Ceramics are very fragile, so such sharp blows can destroy it. If the ignition angle is incorrectly set or when the air-fuel mixture is excessively enriched, the sensor housing becomes very hot. This causes premature failure.
Less popular causes of failure
Please note that when installing a lambda probe, you cannot use various sealants that are based on silicone. You can also destroy the lambda probe if you try to start the engine many times, making small pauses between attempts. Provided that the engine does not start. This will necessarily lead to the fact that the air-fuel mixture will accumulate in the exhaust system. After some time, it will ignite and create a powerful blast wave. Even poor-quality contact or a short circuit in the output circuit, which can destroy the device. The total resource of the elements ranges from 30..70 thousand kilometers. It largely depends on the conditions under which the operation takes place. The longest service life is for sensors that have additional heating. Most foreign cars use this design lambda probe. Symptoms of malfunction (Ford Focus 2 or Skoda are in your possession) are the same. Therefore, you can diagnose yourself, if you correctly recognize all the symptoms.
Frequent sensor breakdown
Among the most popular failures, an idle heating element, as well as a loss of sensitivity, can be noted. Due to the latter, the performance of the device is reduced. Most importantly, try not to replace the lambda probe with any simulators. The electronic control unit will not be able to recognize someone else's signal. Therefore, the correction of the fuel mixture by this simulator will not occur. Please note that if the oxygen sensor has successfully worked in the conditions of our country (low-quality gasoline), moreover, its service life is already clearly more than three years, then you can not even contact the diagnostician. It is immediately necessary to replace the lambda probe. Signs of malfunction Skoda shows clearly with a range of over 70 thousand km. Some models of oxygen sensors may even have a resource of just over 30 thousand kilometers.
How to determine if a sensor is defective
If there is unstable operation of the motor at low speeds, it feels as if the engine is "troit". And at the same time, gas mileage increases, car dynamics deteriorates. Cracks coming from the catalyst are often heard after you shut off the engine. It is also possible to increase (significant) the temperature of the catalyst itself. Sometimes it is so heated that the metal simply heats up. In some vehicles, malfunctions can also be judged by the Check Engine warning light. Only, unfortunately, not all electronic control systems allow us to identify and indicate the malfunction of this element.