When is this necesary? and hows it done exactly.. ?

 

there's couple of ways, the simplest is to pull the negative cable out of the battery for 5 second, put it back on and you're done.

another way is to pull the ecm fuse, but you need to wait for a little bit and you'll need to step on the brake panel couple of time.

 

ok sounds easy, but are there any benifits to it or anythin? and when should it be done..

 

if you had a CEL and you think your repaired the problem you should reset the ECU. The ECU keeps the CEL code in its memory.

For example, if you start your car and the CEL comes on, you shut it off and restart it and it doesn't come. (you would be like damn what was wrong). If you then jump the connector it should still have the CEL in its memory.