Vehicles that have an Active Noise Cancelling system are prone to encounter sound issues when an after-market subwoofer is installed. The sound issue can be described as a hum or low-frequency tone. To understand why this is happening it's important to understand how the ANC system in a vehicle works.

The ANC system's main job is to pick up on any internal/external low-frequency sound, such as engine/road noises, and block them out. The signal is sent to its ANC processor to produce a reverse phase audio signal and is sent back to the speaker system. The inverted phase signal will cancel out the internal/external low-frequency sound, blocking out any unwanted noise.

When you add an aftermarket subwoofer into the mix the ANC system hears the subwoofer output as being part of the engine/road noise. The ANC system believes the low-frequencies being emitted by the subwoofer are part of the unwanted noise and this leads to the ANC system producing an out-of-phase low-frequency signal to block the sub's output.

To identify if your vehicle has an ANC system you can do one of two things.

1. Look up your vehicle's specifications online and verify if an ANC system is installed.
2. Drive your vehicle, play music, put your vehicle in park, and then either turn off the engine or open your door. If the subwoofer plays as it should you'll know you have an ANC system.

To fix the sound issue you'll need to disable the ANC system. You can accomplish this by doing one of three things.

1. Contact your dealership to see if they can disable the ANC system
2. Use an ANC Bypass Harness
3. Disable the ANC system yourself