How to Reset the Codes on GM Cars

Error codes in a General Motors vehicle will appear because the vehicle is having some sort of mechanical or electrical problem that needs your attention. The error codes trigger your error lights, such as you check engine light, to come on in the dash and alert you to the problem so that you can repair the car. However, the error lights in many vehicles do not automatically turn off after you have repaired the original problem. Many GM vehicles require you to reset your car's computer or erase the codes manually in order to make those pesky error lights and codes go away.

Things You'll Need

  • ¾ inch wrench
  • Code reader

Vehicles Manufactured Prior to 1996

  • Open the hood of your car. Locate your battery.

  • Disconnect the battery cable that is attached to the negative terminal, then disconnect the battery cable that is attached to positive battery terminal. Do not let the cables touch each other or the car while the battery is still attached.

  • Let the car sit for 30 minutes. This will make sure the computer resets.

  • Reattach the battery cables, positive first and then negative. Turn on the car. If you fixed the problem prior to resetting the car battery, then your error codes will have been erased and your error lights should have turned off.

Vehicles Manufactured After 1996

  • Hook your GM car up to an automotive code reader. Scan for codes.

  • Electronically erase codes using the code reader. The exact process for doing this will vary depending on the make and model of your code reader, but all code readers have an erase/delete function.

  • Remove the code reader from the vehicle, allow it to sit for several minutes and then start the car. If the codes were properly erased and the problem no longer exists, your error lights will be off and the codes will no longer come up when you can your car's computer.