Engine Control Unit also popularly called a Brainbox is a small computer installed in modern cars that serves as a central control unit which monitors and regulates the functions of the engine, transmission and other crucial parts of the car. That is why it can be frustrating when issues arises with a car and may be misunderstood for electrical or mechanical problems. Where as in fact it is a faulty or bad ECU. Like every other components of the car, the ECU is subject to wear and tear over time. That is why when difficult technical issues arise, you ,may need to pause and check the ECU. This will save you unnecessary costly repairs and waste of time. Below is a simple guide of how to test if your ECU is bad.
The short video below is a simple and effective way of testing if your ECU is bad.
The second video below further explains how to know if your ECU is bad.