Good morning everyone, I love modays.

So I took my bonnie to autozone, for an error code scan and found Evap emission control system malfuction, code P0440. It'* been going on and off for a while, but autozone said that the service engine light has to be on for the scanner to read error codes, fortunetly it came on over the weekend and took the car right away, and it read that code. Question... would the computer hold error codes in the memory? Does the compurter have a memory? Does the scan tool only reads codes when the SELight goes on??

Thanx everyone...

The PCM should store codes. If my memory serves me correctly it will hold an error code for something like 60 car starts. If the code hasn't returned by then it will clear it. You don't need the SES light on either to read it. There are some codes that the computer will store without throwing a code too. You should be able to plug in any good scanner and it will tell you first thing that there are stored error codes.