What is Engine Control Unit in Cars? What Does It Do?

What is Engine Control Unit in Cars? What Does It Do?

The operating principle of four-stroke engines is based on a complex gas exchange to operate safely, efficiently, and with low emissions. This means that as much fresh air as possible or the fuel/air mixture must be taken into the cylinder during the intake stroke. On the exhaust stroke, the exhaust gases must be evacuated as quickly as possible. In four-stroke engines, valves control the gas exchange. The crankshaft that drives the camshaft also actuates the valves.

All the components controlling fresh air/fuel intake and exhaust gas output are known as engine control units.

The engine control must open and close the valves at exact points in the cycle time. In this way, the necessary power and torque requirements determined in each working time/cycle are met while simultaneously minimizing fuel consumption and harmful substance emissions.

There are different design solutions for engine control; gear wheels and vertical shaft are two examples. Today's engines only use overhead camshafts driven by a timing chain or a timing belt. Abbreviations such as OHC, DOHC refer to this technology: OHC: Overhead Camshaft, DOHC: Double Overhead Camshaft.

Depending on the engine's design, other auxiliary components such as an oil pump or a water pump (circulation pump) are also integrated into the engine control. Motor control components are subject to high levels of stress and strain. Typical wear parts in this context are camshafts, oil pumps, belt drive components, or valves.


The engine control unit is one of the most important and technically advanced vehicle systems. Especially for engine parts, the margin of error is zero. If there is damage to the individual components of the cam chain or belt drive, the elements in its immediate vicinity must be replaced at the same time (for example, chain tensioners and rails in chain camshaft systems; tensioner roller (tensioner bearing) and water pump in belt camshaft systems). The material quality of all engine control components is decisive if one wants to be confident that the engine is running smoothly.

Environmental Protection

Gas exchange in four-stroke engines significantly affects fuel consumption and pollutant properties and increases engine power. The manufacturer's specifications determine fully functioning engine control and timing (assignment of crankshaft positions to camshaft positions), so environmental protection plays an important role.


Thanks to modern manufacturing techniques, the engine control components of modern vehicles are designed and sized for the vehicle's life. For this reason, deterioration of wear parts such as camshaft, valve tappets, and rocker shaft is slowed down. For example, only certain parts (such as surface layers) are hardened by induction; the core of the metal part remains untouched.

Adhering to the service and maintenance intervals prescribed by the manufacturer is indispensable if engine control is to be relied upon to meet performance expectations for the vehicle's service life.