Although the original battery on my '99 Cavalier is still OK, I'm going to change it soon. Are there codes that will have to be reset? Or will they reset automatically through use? Or is there a way to prevent the loss of codes? Or on a car this old are there any codes to worry about? Thanks.
I guess the first question is "Is your Service Engine Soon" light on?
If it is then I would take your car to a local auto parts place and have them read the error codes from your computer and see what they say. When you replace your battery it will clear your computer of error codes and depending on the problem and if it still exists then they may be automatically reset into the computer after you install the new battery and you drive your car for a while, at which point your SES light will come back on. If it does come back on, you can go back and have the new codes read and see if there are any new ones or if any old ones did or didn't return.
If the light is not on, then don't worry about it. There is nothing you have to do to your computer (like setting codes yourself) when you install a new battery. Codes are only set into the memory if something goes wrong that is monitored by the computer. You do not have to adjust, set, re-tune, or reprogram your car's computer at all.
The loss of electrical power when you replace your battery may cause your computer to fall back to it's default settings, and if it does it may run a little odd until it relearns the driving and engine conditions. This is perfectly normal.
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