If i disconnect the battery and let the car sit for a while, will the ecu still remember the old codes?
What's the difference between clearing your code and resetting your ecu?

no you can't reset it like that. resetting, clearing is the same thing you have to either manually reset with a screw driver or with a scanner.

yea C MAX is right. My buddy just went to autozone and they reset it for free.

I have to disagree with the other two.

If you leave it disconnected long enough (like over night) it will reset. Any CEL and get rid of any codes.

you could only do that with the later yrs. i tried that already don't work.
i had my battery disconnected for 2 mths while my car was in the shop
and when i put the battery back in the light was still on. if this is true i apologize for the mis-info

disconnecting the battery over night worked for me.

I don't think they are the same thing. Resetting the ECU clears the codes.
disconnecting the battery causes the ECU to read everything like it is a new thing. It starts learning instantly.

its not the same on '97s, i had my battery unhooked over night and the sel was still on, it only takes like 3 minutes to reset the ecu anyways, might as well do that

Well, I cleared my codes and new ones haven't showed up.

I guess I'll just wait... I mean, the ecu is gonna learn again sometime or another, right?
I wonder how long it will take.... (to adjust to KS and intake)

well my quetsoin to you guys is, shouldnt the light come back if something is wrong regardless of leaving it off for an hour or 2 months? if it sensing something wrong even after being reset when you start the car, itll show a code, but if you replace lets say an O2 sensor and then take off the terminal for a few hours, will the CEL still stay lit?