In this video, I will do a test that has never been done before about the oxygen sensor. I think it will be very enlightening especially for those who failed the exhaust inspection due to lambda values ​​and those who will take the inspection. Oxygen Sensor is one of the sensors that ensure the efficient operation of the engine. It is a device that analyzes the smoke coming out of the exhaust and analyzes the air/fuel mixture and measures the amount of oxygen in the fuel. It sends the measurement it makes to the ecu and provides instant adjustment of the air-fuel mixture that should go into the cylinder. Thus, it prevents our vehicle from burning too much fuel or the engine from operating unbalanced by taking too little fuel. It ensures the most efficient and stable operation of the engine. So what kind of test will we do? I had my vehicle inspected for exhaust a short time ago and the lambda values ​​were high but they were just at the limit and the vehicle passed the inspection. Of course, this came to my mind, there is no problem with the fuel in the car while it is driving, why is this value high? I asked the officer there about this. He said it does it from the oxygen sensor. There are sensor cleaner fuel additives or remove the sensor and clean it and it will be fixed. Of course the vehicle passed the inspection, I didn't do anything to the sensor or anything like that, it just sits there. Now I'm going to do something like this, I'm going to put the vehicle in an exhaust inspection before cleaning the sensor. We'll get the lambda values ​​there. Then I'm going to clean the sensor and go in for an exhaust inspection again, let's see if there's an improvement in the values ​​when I clean it, we'll all see that together. First, there's a test I learned from researching on the internet, I'm going to do it using a multimeter to check if the oxygen sensor is sending the correct signal. I'm sticking a pin into the cables that go into the sensor socket, we'll read the voltage coming out of these cables. The oxygen sensor sends a voltage between 0.1 volts and 0.9 volts to the ecu. For example, if the voltage is 0.2, the ecu detects a lean mixture and increases the fuel going to the injectors so that the vehicle doesn't stall. Or if the voltage is 0.9, this time the ecu detects a rich mixture, this means that our vehicle will burn a lot and pollute the environment a lot, in which case the ecu reduces the fuel. When the vehicle's engine is hot, the value that should be is 0.3 volts to 0.6-7 volts, which is considered normal. Look, the sensor is currently 0.38 volts, let's say 0.4. It looks ideal, so there is no problem when you look from here. But what if this sensor is dirty and cannot measure accurately? In other words, if the voltage is actually 0.8-9 or even 1 and above, but the sensor is dirty and reads normally, but the vehicle does not turn on the fault light because the ecu sends a normal signal. When you go for an exhaust inspection, when the values ​​are high, of course it is a surprise, and if you fail the inspection, you are in the hands of the masters. It was a bit confusing, but I hope I was able to convey what I was trying to do to you correctly. In short, I want to test whether cleaning the sensor works or not, or how much it works. Now let's go to the exhaust inspection. It is really a very bad situation for your vehicle to fail the exhaust inspection. I have friends around me who have experienced this. First of all, you need to solve this problem in a very limited time. You don't know what the problem is exactly, for example you go to a mechanic and he says have the valve adjustment done. Someone says the catalytic converter will be changed. Someone says the sensor will be changed. These are expensive parts. If you are currently experiencing an exhaust inspection problem, I would say don't change such parts immediately, at least don't change them without being sure. After explaining the test I will do, I would like to thank the Otopratik Izmir Gaziemir branch for helping me without charging any fee. Here, before the sensor cleaning, we put the vehicle in for an exhaust inspection to get the exhaust values. As you know, a special tool is needed to remove the oxygen sensor, usually a 22 mm socket holds the sensor in most vehicles, but since the cables on it are not removable, you can find a slotted tool that will give that cable out from the side, such as an oxygen sensor socket, everywhere. Removing the sensor turned into a separate adventure. Since the exhaust constantly heats up and cools down again, the sensor is unfortunately welded there. In other words, if you try to remove this sensor, it is very likely that you will encounter such a problem. I started the engine and warmed it up in order to remove it without breaking it. I sprayed wd40. It still didn't help. I kept loosening it a little and spraying vd40 again to make the screw release itself. Eventually, I removed the sensor with difficulty, but unfortunately, as you can see, it wrapped the teeth. I went to the lathe to have the sensor cut new teeth. Anyway, what was our main job, cleaning the sensor. I made the sensor completely clean using brake pad spray and a soft brush. Judging by the condition of the liquid in the container, I can say that there was no dirt on the sensor as I expected. After all this adventure, after cutting new teeth on the sensor and putting it back in its place healthily, we are back at the exhaust inspection station.