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5 Symptoms of a Bad Car Audio Capacitor & How To Fix It


If you really want to understand what are the symptoms of a bad car audio capacitor, then this is the article for you. We will go over some of the most common ones and their solutions.

Installing a strong aftermarket car sound system with audio amplifiers, subwoofers, and other electrical components can make it difficult for most car electrical systems to keep up with the raised power demand.

Do capacitors go bad in the end? Keep in mind that car audio capacitors go bad eventually. They are accessible to stabilize voltage and stop higher voltage spikes in audio play and fix infrequent car electrical system concerns like multiple headlights dimming.

With an electrical issue, it’s preferable to upgrade the car’s battery to add more power than install a capacitor. There are different capacitor types, but almost all of the caps suffer from the same issues.

In most scenarios, it is best to install a capacitor to deal with short bursts of added electricity from your audio system since its purpose is to polish bursts of electrical current and adds additional power capacity to your car.

What is a Capacitor, and How Does It Work?

A car system capacitor was once called a condenser. In a car audio system, capacitors are also referred to as stiffening caps or simply caps and are utilized to help the charging system of your car keep up with the sound setup.

A capacitor is a short-term storage tank for electricity, and it will consume, collect, and send electricity at a fast pace, ultimately leveling spikes in a circuit’s voltage.

The purpose of a capacitor is to smoothen an electrical signal. In a stereo system, a capacitor can stop other components from being affected. For instance, it can stop lights from dimming when the subwoofer provides loud bass sounds.

A capacitor will also deliver a thrust of power to the audio component to stabilize the current and stop the dimming lights. Do the capacitors improve sound quality? Yes, the average capacitor also has the ability to reduce noisy signals and sustain power during heavy loads.

Top 5 Bad Car Audio Capacitors Symptoms

A capacitor stores power in an electric field, while a battery stores power chemically. Both are used as power supplies in different types of electrical circuits. There are a few signs that tell you if the audio capacitor is bad, including the following:

#1 A change in sound quality

Most of the time, you will start to notice a poor bass response performance or a noticeable muddy sound coming from your car stereo system. This happens when the car does not have enough power due to the high amount of current draw from the amplifier.

Something to note is that these electrical devices are typically used to filter out some high frequencies. When there’s a problem, you could notice that the high frequencies may sound distorted, or you may hear a crackling sound when turning the volume up or down.

#2 Your aftermarket car stereo doesn’t turn on

Bad car audio capacitors can affect your car radio and other electronic devices that are powered by your car battery. However, you would need to double-check the car radio to see if you do not have a blown fuse.

#3 Unexpected voltage drops

You should frequently measure your cap with a voltage meter to ensure it’s not damaged. Remove the power cable and test to see how many volts the capacitor can hold. Wait ten minutes and retest the unit to see if it can hold voltage.

If you notice a voltage drop, it means that the capacitor is no longer functioning as intended and needs to be replaced. This also means that it cannot accumulate the same amount of electric charge it could when it was new, so its capacitance and power delivery has diminished.

#4 Dimming headlights

When your power consumption exceeds what your alternator can handle, your lights will dim. At this point, the car reaches your car battery for extra power, and if the battery cannot meet the demand, your lights will dim or flicker.

This is where a capacitor comes in to store power and release it when needed to help stabilize the voltage. If your capacitor is not storing energy properly, your headlights will dim when the bass hits hard.

#5 Electrical issues

The idea of adding a capacitor is to mainly provide at least as much constant current as your electrical system demands on average and extra headroom when you really need it.

When an audio capacitor is bad, it is not able to stabilize voltage, and it does not prevent spikes in audio signals. As a result, you will experience electrical issues.

You may also notice that other devices in your car, such as the radio or amplifier, are not working correctly. To avoid electrical issues, connect the positive terminal of the cap to the positive terminal of the car battery.

When Is It Time to Replace Your Car Audio Capacitor?

Capacitor failure is very common, and it is one of the most frequent issues with car radio systems. It may be time to replace your bad capacitors when you experience the following:

The capacitors cannot keep up with demand

If this occurs, and you don’t have enough electricity remaining for other components of your car’s electrical system, there will be significant consequences, such as braking incapabilities or losing control of the steering while driving at high speeds.

The capacitors are draining faster than they must

If the capacitors in a car audio system are draining faster than they could charge up it could be because of wear and tear on the system. However, it can also suggest a concern with how much energy your car needs overall (for instance, if you simply installed a subwoofer).

However, this usually happens when the system has too much demand, such as an amp that’s drawing more power from the extra battery than it should.

Common Signs You Need to Change Your Car Audio Capacitor

Your car audio system might be working fine, but you cannot hear the music that well. That’s often caused by a malfunctioning capacitor that should be replaced instantly. The capacitor is in charge of offering proper power to the speakers.

Take note that car audio capacitors are composed of two metal plates that store energy along with a dielectric in between them. The car audio system operates by transmitting an electrical signal via the circuit and into the capacitor, where it lies until required.

It stores sufficient power to create music from your car’s radio or CD player without needing more electricity continuously running through it as other parts of your car do:

Here are the most common symptoms you need to go to change your capacitor involve:

  • There are visible cracks around the capacitor
  • Your headlights may stay on after turning off the engine
  • You see a difference in sound quality whenever playing any kind of media on the stereo

Take note that a car audio capacitor is made of power from the spare battery and transmits it to the speakers when necessary. That can include an emergency call over a hands-free system, music, or any other sound coming through your stereo.

If you begin noticing such signs of needing a new one, it is time to handle this small but essential component. You would also like to change yours about every six years for the best performance in every aspect of your vehicle’s entertainment system.

What Factors Causes a Capacitor to Fail In Your Car Audio System?

As with all equipment, a capacitor does not live forever, and its lifespan depends on different conditions and factors. For example:

Under typical circumstances, such as extreme weather conditions and general vehicle movement, a ceramic, solid-state component may endure for years.

However, long-term moisture in the air or mechanical stress may cause failure. If the capacitor of your car audio systems surpasses its suggested Working Voltage Direct Current rating, the electrical component will fail.

What Would a Capacitor Failure Look Like?

Take note that a capacitor is considered to suddenly stop working when there’s a leaking unit failure and slowly lose its capability, particularly mismatched or low-quality components.

On top of that, large capacitors degrade with time. The lifespan is much longer, but it’s still dependent on the same conditions. End-of-life criteria are often measured by the number of charge or discharge cycles and range from 100,000 to 1 million cycles.

If the problem is a major electric power supply concern, you may need to upgrade the existing battery or include a second battery rather than installing a capacitor. By upgrading the car battery, you will stop electrical problems and boost the power supply capability of your vehicle.

How Often Should a Car Audio Capacitor Be Replaced?

Everyone seems to have a different perspective on when their audio capacitor has had plenty. While some people think their capacitor is not up to the task if it is not within twenty-five percent of its specification. Others assume theirs is just good as long as it has not blown up.

Manufacturers suggest replacing the main electrolytes of your car every ten years, even when it still seems like they are running in good condition. That is because older models may not meet present specifications, not necessarily because they’re anticipated to fail.


Q: Do Car Audio Capacitors Go Bad?

Car audio capacitors are made to last the lifetime of the car. Do you notice a change in sound quality? If your aftermarket car stereo does not turn on, it could be an indication that one of the components is falling.

It is not as typical for capacitors to die on vehicles, even though it does happen. You will find many other symptoms to look out for if you believe yours is going bad.

  • Noise or distortion in sound from the speakers when they are supposed to be silent.
  • An aftermarket car stereo head unit does not power up or turn off by itself occasionally while driving.
  • Poor-sounding stereo unity between left and right channels, even when the volume is set at maximum.

If any of the above does not happen often enough for you to notice them happening repeatedly, your cap could still have low voltage output. Make sure they are always tested.

Q: What Can Impact the Durability of a Car Audio Capacitor?

There is no specific answer to how long a car audio capacitor would last, but it is a smart idea to become familiar with what factors could impact its lifespan.

All capacitors are likely to fail at some point, as they depend on a fluid that could go bad or evaporate. When that takes place, it can result in failure.

Running at higher temperatures than the maximum temperature rating for the audio capacitor could possibly wear it down sooner. Indeed, the make of the capacitor is the major factor in how long it will last.

A quality-made capacitor can last a little bit longer than anticipated. On the other hand, a reasonably manufactured model could malfunction in its first year.

Furthermore, voltage application is another thing that could weaken the lifespan of your audio capacitor. Every capacitor has a rated voltage, and it is essential not to go beyond this.

Other factors that could cut the life of electrolytic capacitors are the following:

  • Storage environment
  • Capacitor tolerance specifications
  • A voltage that exceeds the limit of the car audio capacitor
  • Frequent reverse voltage
  • High leakage current
  • Frequent charging and discharging cycles

Learning the proper ways of charging your car audio capacitor will help improve the lifespan and efficacy of your capacitor as well as its overall performance.

Final thoughts

If you think your capacitor is bad, then you would like to do some testing to verify that. You could test a capacitor for leakage by putting it in water and see if bubbles form around the terminals or speaker wires. If they do, then it is no longer safe to use. You must also change it right away.

When changing audio capacitors on your car audio system, ensure the new ones are rated for operating at 12 volts DC. That will guarantee that they can deal with all of the power flowing through them without becoming damaged by excess voltage or overheating.

For best performance, replace your capacitor every ten years. Over time, the capacity of the car audio capacitor will worsen, making it less practical. That means you may like to change it. As a rule, you must change your capacity every ten years.

Last Updated on: June 13, 2023

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