I got a link to the ECU and how to reset check engine lights, and read codes. But what exactly does it do besides that? Does it reset all the sensors or something? Kinda like a reboot on a computer?

 

 

http://www.linkecu.com/

 

Basically it is a computer that gets input signals from sensors that measure things like throttle position, temperature, knock and oxygen (emissions). It uses this information to control outputs such as injectors and spark firing so that the engine performs at its optimum capacity. The ECU also has a memory and is programmable. The ECU cannot usually reset a sensor, it only reads the values coming from that sensor. If the values are not as expected by the processor you may get a CEL. When you reset your ECU you are resetting the processor and not the sensor. If the sensor continues to send values that are out if it's programmed range the CEL will be activated again.

That's the best I can do for a short explanation.


This may explain it much better.
http://en.wikipedia.org/wiki/Engine_Control_Unit

 

One other thing you can get a CEL due to the value provided by a properly functioning sensor or the sensor itself may have failed. Example is an oxygen sensor, it can cause the ECU to throw a CEL because the emissions are not within an acceptable range or the emissions may be fine but the sensor itself is faulty. I believe the ECU may test some of the sensors when you first turn the car on. As is probably obvious by my post I only have a basic understanding of the system.

 

woops. I read it as though he got a Link ecu lol but he just a code scanner /smack self

 

and thats a pretty good explanation man, right on.

 

You should really search before you post things. If you were to do a Google search for the ecu uses you could have found out most of these things for yourself. Don't mean to sound rude its just that if you searched and then asked when you don't understand a certain thing about what you read. Help yourself first.

 

the ecu doesn't do anything. Oh wait its the brain of your car. Nope, doesn't do anything besides show codes.

 

Please search these basic questions. Many simple car explanations car be found on www.howstuffworks.com