1. Check the audio settings: Make sure that the subwoofer is turned on in the audio settings of your car.
2. Play a bass-heavy song: Play a song that has a strong bass and listen for the subwoofer's response. If the subwoofer is working, you should be able to feel and/or hear the bass.
3. Check the subwoofer's wiring: If you cannot hear or feel the bass, you should check that the subwoofer is connected correctly and securely to the amplifier.
4. Check the subwoofer's power: Ensure the subwoofer is receiving power by disconnecting the subwoofer from the power cord and reconnecting it.