What does the computer in a car do?

All cars manufactured today contain at least one computer. It is in charge of monitoring engine emissions and adjusting the engine to keep emissions as low as possible. The computer receives information from a many different sensors, including:

  • The oxygen sensor
  • The air pressure sensor
  • The air temperature sensor
  • The engine temperature sensor
  • The throttle position sensor
  • The knock sensor
  • The oxygen sensor

Using the information from these sensors, the computer can control things like the fuel injectors, spark plugs and the idle speed to get the best performance possible from the engine while keeping emissions low. The computer can also sense when something has gone wrong and can inform the driver with the "Check Engine" light. A mechanic can read a diagnostic code from the computer and fix the problem.


Depending on how expensive the car is, there can be all sorts of other computers. For example:

  • There is probably a computer controlling the automatic transmission
  • If the car has anti-lock brakes, there is a computer reading the wheel speed and controlling the brakes
  • Many air bag systems have their own computers
  • A car with keyless entry or a security system has a computer for these systems
  • Advanced climate control systems often have computers
  • Some cars now have motorized seats and mirrors that can remember the settings for multiple drivers, and these contain computers
  • Any radio or CD player with a digital display contains a computer of its own
  • Cruise control systems use computers

In other words, a modern luxury car is a rolling computer network. It is amazing how many embedded controllers a car can have.

So what was the deal about whether our cars would start on January 1, 2000? Nothing. The computers in our cars have no idea what today's date is because it is irrelevant to their calculations. If you take the battery out of your car to replace it, all of the computers lose power. Your radio, for example, may forget its preset stations. However, you don't have to reset the date on any of these embedded computers because none of them care.

Here are some interesting links: