I have a 2005 Chevy Cavalier and I was wondering if I took my car down the to the Chevy dealer what they would do to reprogram my ECU. What are the benefits? What do they change?

What do you want them to do with it? They probably aren't going to do a thing for you. If you are looking to mod the ECU, read this first:

The HP Tuners FAQ

Kevin Carnahan wrote:I have a 2005 Chevy Cavalier and I was wondering if I took my car down the to the Chevy dealer what they would do to reprogram my ECU. What are the benefits? What do they change?

They'll just put the stock tune back on it, I.E. nothing. If you want to retune your ECU for performance find a JBO member near you that has HPTuners.

What are your intentions?

Like Tink said, performance wise, a dealer won't do anything for you, HPT is the way to go...though a dealer can supply you with an updated version of the stock flash, occasionally they make subtle changes to the files to address certain issues, but I can't think if any significant changes that have been added to the flash update in the past several years that would be worth going in for.

If you aren't making any performance mods, and there is nothing wrong with your current ECU, then I would just leave it alone.