ECU (Electronic Control Unit), also known as "trip computer" and "vehicle computer". In terms of use, it is a special microcomputer controller for automobiles, also called a special single chip microcomputer for automobiles. It consists of microprocessor (CPU), memory (ROM, RAM), input/output interface (I/O), analog-to-digital converter (A/D) and large-scale integrated circuits such as shaping and driving, just like an ordinary single chip microcomputer.

At present, ECU is not only used in engines of some mid-to high-end cars, but also can be found in many other places. For example, anti-lock braking system, four-wheel drive system, electronically controlled automatic transmission, active suspension system, airbag system, multi-directional adjustable electronically controlled seat, etc. Are equipped with their own ECU. With the improvement of automotive electronic automation, ECU will increase day by day, and the circuit will become more and more complicated. In order to simplify the circuit and reduce the cost, a technology called multi-channel communication network is adopted to transmit information between multiple ECU on the vehicle, and the ECU of the whole vehicle forms a network system, that is, CAN data bus.

To put it bluntly, the performance of the engine can be changed by brushing ECU (changing the computer data of ECU).