Why Does Subwoofer Vibrate When Car Is Off? (Solved)

Subwoofers enhance the audio experience in your car. They are a key component if you want to upgrade your vehicle’s stereo system. However, they can develop some issues that can be frustrating.

Some drivers might notice that their subwoofer vibrates when the car is off. Why does this happen? Let’s find out.

Why Does My Subwoofer Vibrate When My Car Is Off?

If your subwoofer is vibrating when your car is off, it can be because of reasons such as suspension, wiring, and RCA issues.

car subwoofer enclosure boot
Subwoofer enclosure in a boot of a car

Here is a deeper look at some of the reasons why this could be happening.

1. Wiring Issue

A wiring issue is one of the most common causes of a vibrating subwoofer when you switch off the engine. When you install your subwoofer, it has to be wired to the car; therefore, when this is done poorly, you’ll have an issue.

According to some car owners, you can solve this by moving the remote wire to another source.

The remote wire instructs the amplifier to turn on each time you switch on the stereo. Therefore, if the remote wire has an issue, it could contribute to the vibration.

2. Loose Suspension

Some car audio woofers are fitted with an extremely loose suspension to make them loud at low frequencies. While this is ideal if you are looking for a seamless audio experience, it can cause the subwoofer to vibrate when the vehicle is off.

When you switch off the car and close the door, the air pressure will spike in your vehicle. This pressure spike can cause the woofers to vibrate for a while because of the loose suspensions.

3. Bad RCAs

5m performance auto RCA cable
5m performance auto RCA cable

Your subwoofer is connected to an AV receiver or amplifier using an RCA cable. Therefore, having a set of bad RCAs could affect how your subwoofers behave when the car is off.

You can try replacing the RCAs when this happens to see if the problem stops. However, if it persists, you can check other factors, such as the wiring.


Why Does My Subwoofer Get Louder When I Turn Off My Car?

If your subwoofer gets louder when you turn off your vehicle because of a grounding issue.  This happens based on the type of amplifier you are using on your car.

The subwoofer gets loud because of a sudden voltage drop that causes a ground loop. This loud noise is popular with lower-brand stereos or amplifiers. Therefore, you can either ground the wire or buy a good-quality amplifier to fix this issue.

You can also take the amplifier out and replace it with another one to see how it works. Turn the ignition on, switch on the stereo and turn off the engine to see if the issue is gone.

Does the Car Subwoofer Stay Always On?

Your car’s subwoofer is powered by a battery. But does it always stay on?

Generally, most subwoofers have standby and automatic settings. They come with on, off, auto, or standby options.

Therefore, when the subwoofer is not on or off, it’s on standby mode, which automatically switches on when it detects a signal. However, the subwoofer might take a few seconds to switch back from standby mode.

The standby option allows you to save on the battery charge because the subwoofer is only on when needed. 

What to Do to Stop the Vibrations?

Car door speaker baffles boom matt wiring
Car door speaker baffles boom matt wiring

If the subwoofer vibrations become a persistent problem, you can do the following,

  • Determine the source of the vibration
  • Add an automotive sound dampener
  • Change the bass frequency
  • Tighten the loose parts

If you can’t determine the problem by yourself, you can take the vehicle to a professional. A qualified technician can identify the source of the vibration and advice you on the best course of action.

This is essential, especially if it’s a wiring problem. If you don’t know how to fix the wiring, you could worsen the issue, which can be more expensive to fix in the long run.

Can The Subwoofer Vibrations Affect Your Car?

While the subwoofer is usually placed in the car trunk, the vibrations they produce can pose a threat to your interior components, especially if it vibrates too often.

Here are some of the ways the subwoofer can affect your car.

1. They Can Drain the Battery

High amp car battery 12V DC, 110Ah
High amp car battery 12V DC, 110Ah

A subwoofer adds an extra load to your vehicle’s electrical system. The subwoofer and amplifier draw more current than the typical car stereo system because it needs to play more frequencies.

When your subwoofer draws too much current from the vehicle’s electrical system, it will put a strain on your car battery.

Additionally, the battery gets drained faster when the car engine is off because the batteries only get charged when the vehicle is on.

2. Vibrations Can Loosen Car Parts

Renault Scenic left door panel with speaker and connections
Renault Scenic left door panel with speaker and connections

When the volume from your subwoofer increases, it can induce vibrations in the surrounding parts of the vehicle. Some of the parts that will be affected the most are the panels.

Since these panels are attached to the vehicle’s chassis, they can loosen some screws, such as mounting bolts that hold the parts together. Because of the vibrations, the subwoofer can become dangerous to your vehicle.

To avoid such problems, you can add sound dampeners to absorb the sound and vibrations. All vehicle parts will remain intact when you have these measures in place.

3. They Can Cause the Car to Rattle

Rattling in vehicles is a result of low-frequency sound waves transmitted from the subwoofers. This mostly happens when the vehicle does not have dampening material for soundproofing purposes.

These materials are meant to protect your vehicle from resonance and vibrations coming from your subwoofer. You need them because your car’s body is made of a metal shell that can trap sound waves.

Therefore, when the vibration is high, your panels, windows, and other parts will start rattling due to the frequency. You can avoid this by soundproofing your vehicle and finding ways to stop the vibration sounds.

4. Your Vehicle Rear Could Sag

car subwoofer pair boot
Car subwoofer pair in car boot

On average, a subwoofer is usually 8 to 24 inches and comes in varying weights. Most car owners invest in a bigger subwoofer to get better sound.

However, there’s a downside to this because the biggest subwoofers tend to be heavier. Therefore, if you add a subwoofer to the vehicle, it becomes heavier, which can cause the rear to sag.

This is especially common in smaller cars. So apart from the vibrations, you can damage your vehicle by exerting too much pressure on it.

Can Subwoofer Vibrations Affect the Vehicle’s Engine?

Although the subwoofer vibrations could damage other parts of your vehicle, they won’t damage the functioning of the engine.

Your engine is quite sturdy, so vibrations can’t damage it.


Adding a subwoofer to your vehicle can be an exciting experience. However, it becomes a problem when you have issues with the stereo system.

If the subwoofer vibrates when the vehicle is off, you need to confirm whether your wiring, RCA cables, and suspension are in order. Once you identify the source of the vibration, you can quickly fix the issue.

Remember that too much vibration can damage some of your car parts. Therefore, as you fit a subwoofer, ensure it’s working correctly without affecting the vehicle.


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