If the problem has been diagnosed and fixed but the check engine light is still on, either use an auto scan tool or simply disconnect and reconnect the battery. If there is still a problem with the engine, disconnecting the battery and resetting the light will not make the light turn off. Also, if the vehicle's radio has an anti-theft setting, disconnecting the battery may make the radio stop working until a specific code is put in to fix it.
Sometimes a check engine light can go on or remain on even if there is no actual problem with the engine. If this is the case, then the light needs to be reset in order to turn it off.
- Disconnect the battery.
- Reconnect the battery.
Open the hood of the Chevy Cavalier and locate the battery. Remove the cables from both the positive and negative terminals of the battery, and make sure that the cables do not touch each other.
After 5 to 10 minutes, reconnect the battery making sure that the positive cable goes to the positive terminal and the negative cable goes to the negative terminal in the orientation that they were originally in. Restart the car, and if the engine is fine, then the check engine light should be off.