Most any repair shop will do it for a fee. If you are looking for free, try Autozone.
Have vehicle scanned to see if any codes are present
Check for a vacuum leak.
check your manuel
Get a code read out from your engine computer and it will tell you what is wrong.
If the check engine light is on then have it scanned for codes. I could guess you into bankruptsy. It is cheaper to have it scanned and repaired.
Check www.autozone.com, they have a Repair Info section that covers Buick LeSabre with this info.
way to go genius you screwed up the car
Have vehicle scanned to determine the problem
Check the belts. The most common cause of squealing is a worn or loose belt on the front of the engine.
Problem with emission control system - have vehicle scanned to determine the problem
If you are referring to resetting the Check Engine Light then you will need to have someone with a scanner to do it. If you are referring to reprogramming the Engine Control Module then the dealer will do it.
To repair a seat heater on a 2004 Buick LeSabre, disconnect the connector and check for voltage. If there is no voltage, replace the switch. If there is voltage, check for an open circuit.