How long does engine or transmission control modules last?

Control modules can last the lifetime of a car but they can be affected by factors like manufacturing error, high temperature, moisture and vibration.

What are car control units and their functions?

The control units in a car are electronic devices that have programs and algorithms meant to control the different systems of a car. Systems like the engine, transmission, lighting, suspension and so on.

Control modules like ECU/ECM (engine control unit/engine control module) and TCU/TCM (transmission control unit/transmission control module) are very crucial electronic modules that are pivotal to the functioning of a car.

What are the components of a car's control units?

Control units have solid state electronics like the integrated circuits, capacitors, resistors, transistors, inductors and so on. They have programs (hundreds, thousands or million lines of codes) burned into some of those integrated circuit components. Some people have had success with resuscitation of ECM by replacing capacitors because they loose capacitance as they age.

How many control modules a car can have

The ECU is the central and main module that communicates with other modules in the car and it also controls the electronic fuel injection.

In some cars, the ECU controls the transmission too, so there is no dedicated transmission control unit. Cars do have a single ECU for engine management but there can be several other control modules like that of the transmission we mentioned earlier, there are comfort control modules, some cars like the Hybrid Synergy Drives have battery control modules among many others.

Symptoms of a bad control module

A faulty control module can make a system that it controls to not operate properly or not function at all.
A fault in the ECU can make the car engine not to operate well or cause a no start situation. A faulty transmission control module can cause a no shift or poor shift.

Does an ECU expire?

We have been asked quite some number of times of how long engine control units can last with common questions like "does ECU expire?" or "does ECU spoil?". Those kind of questions necessitated this article.Control modules especially the engine control modules are generally built to be robust but that does not mean that there have not been cases of manufacturing faults.

One of these problems is that of poor soldering that creates a poor contact or open circuit after some period of use, especially with the effect of heat. These poor solders commonly break at the point of connectors. This fault is not very common but we have fixed some engine control units by resoldering.
We have also fixed an ECU with a broken MAP (manifold absolute pressure) hose. The MAP sensor is embedded inside the ECU and the hose routes from the intake manifold to the ECU. Over time, the rubber material of the hose degrades, it becomes plastic and breaks.

Other causes of control module faults

1. Water ingress to control unit:

Water reaching a control module can damage the module. Control unit of some cars are placed in areas where there are vulnerable to water damage, areas like under the floor mat.

2. Effect of temperature on control unit:

Placing the ECU in a very high temperature environment can damage it. The ECU of some cars are well heat shielded and are even placed on top of the engine. This is commonly done by Mercedes benz.

Control unit lifespan

3. Excessive mechanical vibration of control unit:

Control units are normally well fitted and shocked to prevent excessive vibrations that can damage them.

4. Electrical short circuit affecting control unit:

An electrical short circuit to wires connected to a control module can drive undesirable current into it and burn components in it.

In conclusion, the engine control unit is built to be robust and last the lifespan of the car except there is manufacturing fault of other external faults affect the ECU. Of course, they are not routine maintenance components but they can be replaced when they are faulty.

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