How To Clear A Check Engine Light With No Scan Tool Clearing a check engine light without a scan tool can be done in a few ways, but it's important to note that clearing the light without addressing the underlying issue that caused it to turn on can result in further damage to your vehicle. Here are a few methods you can try: Disconnect the battery: One way to clear a check engine light is to disconnect the negative terminal of the car battery for about 15 minutes. This should reset the car's co