The rainy and storm season causes many cars to fall into flooded conditions or be submerged in water for many hours, even days. According to Mr. Tran Minh Tien - lecturer of Automotive Technology, Dung Quat College of Technology (Quang Ngai), damage on cars after flooding is usually divided into two main groups including mechanical damage and damage to electrical and electronic systems.
The heaviest damage after flooding depends on the level of flooding and how it is handled afterwards. If the car is not waterlogged, electrical and electronic systems are usually the most affected.
One of the important and high-value parts is the car's engine ECU and other electronic control boxes. This is likened to the "brain" of the car, responsible for controlling many important systems. On many car models, the ECU is located in a high position to reduce the risk of flooding.
However, if the car is immersed in water for a long time, water can still enter the interior of the control box. At that time, if the electrical system is still powered from the battery, electronic circuits are very likely to experience short circuits, oxidation or complete damage.
Many manufacturers have enhanced ECU protection by coating the entire circuit board with a layer of glue or silicon to prevent moisture and water. However, this measure only helps increase resistance but does not mean that the ECU can operate normally after prolonged soaking.
After the ECU, the ABS brake system control cluster and ESP electronic balance are also valuable components. This part includes both the electronic circuit and the hydraulic pump motor. When water intrudes, not only the circuit board is at risk of damage, but the internal motor is also prone to rust, reduced lifespan or loss of operation. The cost of replacing the ABS/ESP cluster is usually very high.
In addition to the main control boxes, the car also has many other electronic modules such as door lock control boxes, glass doors, electrically adjustable seats or sensors. These parts can also be affected by water intrusion, although the cost of repair or replacement is usually lower than the ECU and ABS.
In the mechanical group, starters and generators are also often flooded. However, these two parts have a fairly good recovery capacity if removed, cleaned, lubricated, and tested before reinstalling.
For electric cars, the risk of damage after flooding is not lower than internal combustion engine cars. Electric motors and inverters both contain many electronic circuits, and work at high voltages, about 400 V on many current models.
Some electric motors meet IP67 dust and water resistance standards. However, this standard only allows the device to withstand water soaking in limited conditions and time, not designed for long soaking for many days. Therefore, after the electric vehicle is submerged, the entire high voltage system needs to be carefully checked before operation.
Mr. Tien recommends that if the car is flooded, the car owner should absolutely not try to start the engine because it can cause widespread damage to both the electrical and mechanical systems. Instead, you should disconnect the battery if it is safe to do so, contact the rescue unit to bring the car to the garage for comprehensive inspection.
To limit risks, car owners should monitor weather forecasts, proactively move their cars to a high and dry place when there is a warning of heavy rain and flooding. In case you are forced to leave your car in an area at risk of flooding, cutting off the power from the battery will help reduce the risk of short circuits and limit damage to the electronic system.
