What is an Engine Control Unit? | How does ECU Work?

What is an ECU?

An ECU (engine control unit), also known as an ECM (engine control module), is a computerized unit that handles different actuators of the IC engine to ensure maximum performance of the engine. This unit performs this job by reading values ​​from different sensors installed in the engine compartment. It interprets the data of the sensors by using a multi-dimensional performance map (known as a lookup table) and adjusts the engine actuators.

Engine Control Unit

The ECU (engine control unit) ensures the optimum performance of the vehicle. The proper working of the engine control unit is very important for the efficient working of the vehicle.

As ECU goes bad fails, it produces different symptoms. A bad ECU makes the car difficult to drive. As you observe the signs of a bad engine control unit, you must immediately repair or replace it.

The engine stalling and reduction in the engine performance are the most common signs of a damaged ECU. You may also feel problems starting the vehicle and high consumption of the fuel. You may also notice a decrease in engine power.

Symptoms Of a Bad ECU

1) Check Engine Light

The illumination of the Check Engine Light is one of the main signs of a bad ECU. The Check Engine Light installs on the dashboard of the vehicle. However, this warning light may turn on due to many other reasons.

Use an OBDII scanner to detect the problem with your engine control unit. If it does, it could be due to a faulty circuit, sensor, or other electronic parts. Check the error code to identify the problem.

2) Engine Stalling

The vehicle engine may have stalling issues due to a bad ECU. In such conditions, the vehicle may stall or misfire when you are sitting in front of a traffic light.

This stall and misfire pattern can be completely random, and no troubleshooting patterns are available. This issue may cause when the ECU sends wrong information to the engine, which can result in an excessive rate of intake of air or fuel.

3) Poor Fuel Economy

The ECU ensures a balanced supply of the air-fuel ratio to the engine. As the ECU goes bad, it delivers an imbalanced air-fuel ratio that highly affects the engine performance. In such a situation, the engine control unit may unintentionally deliver excess fuel to the combustor and take a large time refueling at gas stations.

So, you always keep an eye on the consumption of the fuel so you can be alerted if something goes wrong. When the car burs more fuel, it expels more exhaust gases into the environment.

4) Reduction in Engine Performance

The engine performance highly depends on the ECM. The reduction in engine performance is one of the major signs of a bad engine control unit (ECU). As the ECU goes bad, it doesn’t deliver enough fuel to the combustor. In such conditions, you will notice some performance issues.

The vehicle may also start vibration, especially when attempting to climb or tow a hill. Therefore, you replace the faulty ECU before the car stops working completely.

5) Car Doesn’t Start

The worst that can happen due to an ECU malfunction is preventing the vehicle from starting. At first, you may find the vehicle hard to crank until it finally stops.

The inability to drive the vehicle means a lot, but it is also a symptom of the complete failure of the engine control unit. In such conditions, the ECU doesn’t send a signal to the engine due to that engine doesn’t know what to do.

Engine Control Unit Location

The ECU is most commonly located near or on the engine. However, it is also installed under the dashboard or behind the glove cabin in cars.

However, the ECU is located in several places. However, you may also check the owner manual to find the ECU.  

Function of an Engine Control Unit (ECU)

The engine control unit takes information from various sensors around the vehicle and sends this data to the electric motor. Information to be processed includes engine spark ignition and air/fuel ratio.

This is an important component of modern vehicles, where the ECU handles most of the basic functions. When an engine control unit fails, many problems can arise, or the car can stall completely.

Engine Control Unit Replacement Cost

The replacement cost of the engine control unit varies according to the type of bran and vehicle model. The average replacement cost of the engine control unit is between $480 to $2100. In this cost, the labor cost is between $40 to $220 while the ECU itself cost is from $440 to $1880.

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