The ECU, which stands for “Engine Control Unit”, is one of the most important elements of today’s car. Nowadays, the role of the ECU is crucial in many new cars, because many functions of the car are controlled by it. 

An ECU can be defined as the electrical control unit that regulates the engine of our car, and can also be seen as the heart of the electrical system made up of sensors and actuators. The simplest early ECUs on the market could control the flow or quantity of fuel. 

Unlike the newer ECUs, which control almost all of the car’s systems. This makes it often difficult to find possible faults arising from small electronic faults. In the same way, ECUs have evolved quickly and efficiently, providing different aids, such as, for example, having elements that inform us of a problem; one of the systems performs an analysis when the ignition is started to check if there is any error. In the event that there is a problem with our car, the ECU will let us know by means of symbols that are located on the dashboard of our car. 

What is the function of these sensors?

The function of these sensors is to record the various parameters regarding the operation of our car, such as:

• Engine revolutions.
• The temperature of the system. 
• Throttle position signal, etc. 

These sensors fulfil the task of acting as a bridge to the central system or ECU and transforming these physical quantities into electronic ones. 

What are actuators?

Actuators are the elements which are driven by the ECU and which are responsible for converting the electrical signals received into mechanical quantities. 

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Functions of the ECU in our car

An ECU fulfils several functions to ensure the proper functioning of our car, among these functions we can find the following:

Fuel injection control

An ECU is responsible for determining the amount of fuel to be injected into the engine, based on a short number of pre-determined parameters. If the throttle of our car is fully depressed, the ECU is responsible for opening certain inlets, which will cause the air intake to be much higher. The ECU will inject more fuel according to the amount of air and fuel pressure that is passing through the engine. It should be noted that if the engine of our car has not reached sufficient temperature, the amount of fuel injected will be much higher. 

Controlling the ignition timing of our car

A spark ignition engine will need a small spark in the combustion chamber to initiate combustion. The ECU will be in charge of setting the exact time for this spark to occur, also called ignition timing, in order to provide better power and thus lower fuel consumption. 

Control of valve distribution

Some car engines have valve timing, in these types of engines the ECU is responsible for controlling the time in the engine cycle at which the valves should open. These valves normally open at higher speeds than at lower speeds. This helps to optimise the flow of air entering the cylinder of our car, increasing power, and thus preventing fuel misfiring. 

Symptoms that indicate your car’s ECU is malfunctioning

Your car won’t start

Another symptom that indicates that your car’s ECU is faulty is that it won’t start and has difficulty starting. If the ECU stops working, your car’s engine will have no control unit, and therefore will not start. 

Engine stops

Erratic engine behaviour can be a sign of a faulty ECU, which causes the car to shut down. Such symptoms may occur from time to time, and it may be seen that the frequency and severity has no pattern. 

Check Engine light comes on

If the Check Engine light comes on, it is a sign that the ECU has or may have detected a conflict. Generally this light comes on when the computer detects some kind of problem with the sensors or circuitry. We recommend that you have your car scanned to reveal exactly what fault your car may have.

Problems with engine performance

If the engine’s fuel and timing parameters, which negatively affect performance, become out of adjustment. It should be noted that a faulty ECU can cause our car to have a loss of power and lower fuel efficiency.