How do you turn off service engine soon light on 1998 Lincoln town car?

To turn off the "Service Engine Soon" light on a 1998 Lincoln Town Car, you first need to diagnose the issue triggering the light using an OBD-II scanner. Once the problem is identified and resolved, you can reset the light by disconnecting the negative battery terminal for about 15 minutes or by using the scanner to clear the codes. If the light reappears, it indicates that the underlying issue has not been fixed.