ESP is the registered trademark of Bosch's body stability system. Some other manufacturers also have body stability systems, but they are called differently. There are several reasons for the ESP light on the car to light up:

1. It may be that the stability system off button is accidentally touched, causing the stability system off warning light to light up.

As shown in the picture above, if this light comes on on your car's dashboard, there is no need to worry. This is a warning light that the vehicle stability system is turned off. I must have accidentally hit the stabilization system off button.

The picture above is the body stability system off button on the car. Because the body stability system is an active driving safety system, it is turned on by default under normal circumstances. However, in some cases, the stability system's misjudgment may affect the vehicle's escape. For example, if a car skids after getting stuck in the snow, the body stabilization system will forcibly reduce the engine output, which is not conducive to escaping. Therefore, many cars are designed with manual shut-off buttons, but after shutting down, there will be a clear prompt on the dashboard to tell the driver. The passenger stability system has been switched off. This is for safety reasons to prevent accidental shutdown in some cases.

2. It may be that the body stability system is working.

I guess many people have seen the icon in the red circle in the picture above when driving, especially when there was widespread snowfall some time ago. Many friends will find that this light will turn on when your car skids in the snow. It will light up to indicate that the stabilization system has intervened. However, according to the questioner's description, this possibility is relatively small. But let’s talk about it in passing. Generally, when the vehicle stability system is working, this light flashes and is not always on. So it's easy to judge.

3. The last situation is the worst case: there is indeed something wrong with the ESP system and it reports a failure. There are too many factors that can cause ESP system failure, but the most common one in real life is wheel speed sensor failure.

The wheel speed sensor obtains the wheel speed value through induction and feeds it back to the trip computer. Each wheel has an independent wheel speed sensor. This wheel speed signal is very important. For example, some Volkswagen models are equipped with tire pressure monitoring, but there is no sensor in the wheel. The wheel speed sensor signal is compared with the wheel speed to determine the tire pressure. Moreover, the ABS system and ESP system rely heavily on wheel speed signals. Because these two systems directly intervene in the brakes, and any improper operation of the brakes by a moving vehicle will bring serious consequences, therefore these two systems will report a fault after losing any wheel speed signal. And all went on strike. At this time, the vehicle can still drive normally, but ABS and ESP cannot be used.

The purpose of the wheel speed sensor determines that its working environment is not very good. When we drive through water or wash the car every day, water may enter the plug and affect the normal operation of the sensor.

So when the vehicle's ESP fault light comes on, we can first check the wheel speed sensor. Common faults are poor contact and open circuit of the signal line. There are relatively few cases where it is actually broken. Because the sensor itself does not have much technical content, and the technology is quite mature, it can be said that it will not break unless it is artificially destroyed. Of course, except for some memorized ones.

Now that I have mentioned this, let me mention the vehicle speed sensor, which is different from the wheel speed sensor. The data from the car's speedometer comes from the vehicle speed sensor. There is only one vehicle speed sensor, which is generally located at the output end of the gearbox. Its signal is an essential signal for idle speed control, gearbox control and other systems.

The vehicle speed sensor is mostly located at the output end of the gearbox, which directly reflects the speed of the driving wheels. For example, if our vehicle falls into snow and the driving wheels slip, the speedometer will still display a numerical value, so what the vehicle speed sensor responds to is The speed of the driving wheel. Both the automatic transmission control system and the idle speed control system require this signal value to perform corresponding adjustment operations.