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Why Car Radio Won’t Turn on After Replacing Battery?

At some point, your car battery dies or malfunctions, so you change it, however, after the replacement, your car radio often refuses to switch on.

But why does the radio not turn on after replacing the battery? Let’s find out.

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Car radio may not turn on after replacing the battery because of a damaged fuse, when it is locked, or the battery was installed incorrectly. Fuse or radio damage happens when electrical surges are too high, while a car’s security feature results in a locked radio after battery replacement.

As an Amazon Associate, ImproveCarAudio will receive a small commission from qualifying purchases made through the links in this article.

Tip: Before replacing any car battery, it is worth plugging a memory saver into your car’s cigarette or accessory outlet. You can also buy a memory saver with a built-in battery.

APSG Battery Saver and VSTM OBD II are my favorite and inexpensive options if you are on a budget.

However, if you prefer a complete kit that will not only save memory but will also protect and help with charging the battery, try Li Lead Battery Protector, Ezred Memory Saver on

In this article, I will show you the possible causes of radio malfunction after battery replacement and their quick fixes. Similarly, you’ll gain a better understanding of why these issues happen and other related things.

Radio Malfunction After Battery Replacement

When you replace your battery, two things happen:

  • First, you’re disconnecting your car’s electrically-powered components from their power source.
  • Second, you’re exposing the components mentioned above to a possibly high electric surge when you turn on your car after replacing its battery.

Improper handling and procedures could result in damages to your car from this alone. The sudden electric surge can blow your radio’s fuses or cause internal damage to it. However, that is not where it ends. 

car radio wont turn on after replacing battery

During the whole battery-changing process, you or the person replacing your battery may miss some crucial steps or neglect essential things by accident. For example, you may not know that you need a memory saver during battery replacement to ensure your car’s radio and everything else does not reset. 

When this happens, you will end up with a car suffering from memory loss once you turn it back on. Likewise, you may lose access to your radio, where it will ask you to input an anti-theft code or where you are unable to set its time right.

What Happens When You Disconnect Your Car’s Battery?

The average person wouldn’t usually think about what happens when they disconnect their car’s battery. Since you can power everything on and off without much thought or consequence, you may think the same goes for your car.

However, remember that even phones and computers need to follow proper shutdown procedures to ensure you’ll receive no data loss. Similarly, other electronic devices need their controls switched off to ensure that no damage occurs to them. 

Hence, when you’re disconnecting your car battery, you need to follow proper procedures or risk having the following issues with your car:

Memory Loss Occurs When You Disconnect a Modern Car’s Battery

You may not know about this if you’re only familiar with replacing older car models, but modern cars need a memory saver when you’re disconnecting their batteries.

If you neglect using a memory saver, your car is bound to lose most of its memory within 5 to 10 minutes of battery disconnection. This is because your car’s computer needs constant power to remember your preferences and stored settings.

So, once you finally turn on your car after replacing its battery, you’ll notice your car runs differently and displays different settings. Similarly, your car may even ask you to input a code before you can access and use its computer.

Your Car’s Radio May Ask for a Code After a Battery Replacement

This is a part of a modern car’s security feature: asking for a code before using your radio after you replaced its battery. If somebody steals your car, the code prevents the thief from using your car’s radio, among other things.

You May Experience Starting Problems and Driveability Issues

You spent plenty of time with your car, driving it around and allowing it to know your preferences, and it stored all the information it learned from you into its computer.

However, when you disconnect its battery for a long period, its memory resets, so it forgets your preferred settings. As a result, you may experience driveability issues like a poor-running engine, malfunctioning sensors, weird transmission functions, and other things. You may have issues starting your car, too. 

Your Air Conditioning, Car Radio, and Power Accessories May Enter a Constant State of Malfunction

Your air conditioners act up due to the resetting of your car’s climate control module. 

Meanwhile, your car reset radio isn’t turning on due to memory loss, and your power accessories aren’t working properly because your body control module also reset itself.

Of course, you’re learning these a little too late. Your car may showcase one or two of these issues already, especially the radio malfunction part. However, know that they’re not permanent damages. They’re fixable, but some of them may cost quite a lot.

If you want to watch an entertaining clip that explains why battery disconnection harms your car, check out a short video from Scotty Kilmer:

Why My Car Radio Does Not Work After Changing Battery?

You wouldn’t damage your car’s components if you installed the new battery correctly. However, if you mishandle a part of the installation process, you risk fuse issues and such.

Now that you have a better understanding of what happens when you disconnect and reconnect your car battery, you’ll easily discern why your car radio isn’t turning on after you replaced your battery. I will explain the top three reasons below and suggest ways to fix them.

Car Suffered Fuse Damage

Fuses are short wires with specific compositions and diameters, and they exist to prevent fires, electrical shocks, and other things from happening. When you start your car after you replace its battery, you may blow up a fuse within your radio’s system. That fuse will prevent your car radio from working.

To diagnose if your car radio suffers from a blown or damaged fuse, you’ll need to:

  1. Disconnect your car battery.
  2. Open your car’s fuse compartment that’s usually located behind the radio.
  3. Check each fuse for signs of damage.
  4. Blown fuses often look fried or melted.

Once you determine that your car radio isn’t working after battery replacement because of a blown fuse, you can fix this by replacing your fuse.

To replace your car radio’s fuse:

  1. Consult your car’s owner manual for fuse specifications.
  2. Buy or obtain the specified fuse.
  3. Remove the damaged fuse and place the new fuse in the compartment.

Car’s Security Feature Locked Your Radio

Your car radio may refuse to turn on if the battery replacement activated your radio’s anti-theft feature. Modern car manufacturers placed this security feature to prevent thieves from accessing your car’s computer module, but you may find it bothersome when all you did was replace your battery.

You’ll know your car radio is locked when it shows LOCKED on its screen or simply asks you for a code. You can find your car radio’s code in four ways:

  1. Read through your owner’s manual to check for the code.
  2. Check your car manufacturer’s website for a self-service section that allows you to figure out your radio code by entering your car’s vehicle identification number, year, make, and model.
  3. Reach out to your car manufacturer’s customer service representatives for assistance.
  4. Contact your local dealership for help.

Battery Installation Method Damaged Your Car Radio

As mentioned earlier, you need to replace your car’s battery by following proper procedures and taking necessary precautions. If you skip those, it results in car component damage, including radio damage.

You may try the steps we’ll mention below in an attempt to fix your car radio. However, if those steps don’t work, it may mean that your radio suffered internal damage. Bring it to your local dealership to have it checked.

If your car radio suffered internal damage, your best option is to replace it. 

How to Restart a Car Radio After Replacing the Battery?

Many car radios do not require restarting when replacing the car battery, but some models will be locked and need more attention.

To restart your car radio after replacing the battery, you’ll need to follow a few simple steps:

#1. Start your car and turn on the radio.

#2. If the radio does not come on, try pressing the “Reset” or “Restart” button on the radio itself. This button is usually located on the front of the radio and is typically marked with a “Reset” or “Restart” label.

#3. If pressing the “Reset” or “Restart” button does not work, try pressing and holding the “Power” button on the radio for a few seconds.

If a few seconds is not enough, try to hold it longer, and it should turn the radio off and then back on again.

#4. If the radio does not turn on, try disconnecting and reconnecting the battery cables starting from the negative terminal. This should reset the electrical system in your car and may cause the radio to restart.

#5. If none of the above steps work, you may need to refer to your car’s owner’s manual for specific instructions on restarting the radio after a battery replacement.

#6. If you restart the radio and see the “enter code” or “code” message on display, you need to type the correct code, which is usually four or six digits. Otherwise, you will not be able to turn it on.

Remember also that you have a limited number of attempts, and if you type the incorrect code too many times, the radio will lock itself, and you will have to take it to the service for unlocking.

What to Do When Your Car Radio Won’t Turn On

Besides the quick fixes mentioned above, here are some other things you can do when your car radio won’t turn on after you replaced its battery:

#1. Disconnect and reconnect the pigtail connector or replace it.

Sometimes, all it takes to fix a car radio that refuses to turn on after a battery replacement is the disconnection and reconnection of its pigtail connector. Hence, try disconnecting your connector for about 15 minutes before reconnecting it again, and then turn on your radio.

#2. Check the head unit for power.

If you find no fault or damage on your connections and fuses, check your power wires. Your car has two: one is constantly hot, and the other only heats up when you turn on your ignition. Having these wires on reverse results in radio that won’t turn on, and having them on low or without power means they are broken, resulting in a faulty radio. Replace your power wires if this is the case.

#3. Check radio’s ground connection.

You’ll notice ground loops instead of total failures if your car has ground issues, but it’s still wise to check on it when your radio won’t turn on. To do this, use a multimeter on the head unit pigtail and ground on your car’s body. A poor ground result means the ground itself isn’t the only reason for your radio failure, while a disconnected ground means the ground is at fault.

#4. Test the radio.

If you can’t think of anything else to test and check, connect your ground and power leads to a 12V negative and positive. Replace your head unit or leave it alone, depending on the result.

#5. Check the manual.

Most cars possess complete troubleshooting guides, so there’s a chance you’ll find a solution here.

#6. Turn the ignition key just enough to start your car’s basic functions but not the engine, and then let it sit for 10 minutes.

This is useful if your car forgot your radio’s vehicle identification number and locked you out.

#7. Visit your local dealer and ask them to use their factory scanner to revive your radio.

In some cases, the factory scan tool solves the car radio problem. However, note that this may take a few hours.

#8. Replace your car radio.

It’s expensive to replace your car radio, but it may be the only way if your car radio won’t turn on after battery replacement. This is especially true if your car radio suffered internal damage.

How to Replace Your Car Battery the Right Way

Of course, you learned your lesson when you couldn’t turn on your car radio after replacing its battery. So, you want to learn the correct way of replacing your battery for future reference. Here’s how:

Buy a Memory Saver

A memory saver is crucial to ensure your car’s data remains the same. It charges your car radio and other electric-dependent car components while your battery is disconnected. This prevents memory loss from happening and saves you from future headaches like a malfunctioning car radio.

You can plug your memory saver into your car’s cigarette or accessory outlet, or you can buy a memory saver with a built-in battery. APSG Battery Saver and VSTM OBD II are inexpensive options if you are on a budget. However, if you prefer a complete kit that will not only save memory but will also protect and help with charging the battery, check out Li Lead Battery Protector or Ezred Memory Saver on now.

Don’t forget to arm yourself with goggles and gloves as well.

Connect Your Memory Saver and Plug It Into Your Car’s Accessory Outlet

Of course, you don’t need to plug your memory saver into your car’s outlet if it already features its battery. However, double-check that the memory saver’s battery contains power and ensure that it’s working after you plug it in.

If you’re using a memory saver plugged into your car’s accessory outlet, you may need to turn your ignition on to make it work.

Switch Off All the Other Accessories Within Your Car

You’re using the memory saver to save your car’s most important data, so all you need to connect is your car’s computer part. Hence, switch off your car’s lights, air conditioner, and other battery-powered accessories. This ensures that your memory saver will work as long as possible.

Disconnect Your Car’s Battery

Your exact process of removing your car’s battery will vary on your car’s make and model. However, most cars possess guards and a plastic cover. Sometimes, they may even feature a mounting bracket. Remove these parts with the appropriate tools and proceed with the next steps.

Once you remove the car’s casing, your next step is to disconnect the negative terminal. The negative terminal’s cable must go first. If you remove the positive terminal before removing the negative end, you’ll most likely cause a short within your car’s system. This is because your metal tool may touch another metal in your car when removing the positive end first.

You can figure out which cable houses the negative terminal by looking for the terminals’ minus sign. Similarly, it’ll always be housed under a black cover.

Grab a socket wrench to remove the nut holding the cable’s clamp. Then, remove the cable and place it in a secure place. Ensure that the cable isn’t anywhere near the battery. You can wrap a rag around the terminal for better results so the cable doesn’t hit it.

Next, remove the positive terminal. Its cable is next to the negative terminal, and it’s red. Similar to the negative terminal, ensure that the cable doesn’t touch the battery.

Place the New Battery As Fast as You Can

You can take your time if your memory saver possesses a large battery, but it’s best to be swift when installing a new battery. This reduces the chances of future issues after the installation.

When placing a new battery on your car, reconnect the positive cable first and then the negative cable. Then, double-check if their attachment is secure. Once that’s done, replace the covers, guards, or brackets with new ones.

Finally, switch on your car’s ignition and start your engine. You can now remove the memory saver, and your car’s system should be alright.

You can also view Scotty Kilmer’s YouTube clip for a fast tutorial on disconnecting and reconnecting your car’s battery the right way:


Can a Bad Battery Cause Radio to Not Work?

If your car radio won’t turn on after you replace the battery, it’s often because you need to re-enter the code.

Many newer cars have radios that require a unique anti-theft radio code. 

COding the radio is needed to prevent someone from stealing your radio and using it quickly. Without entering the code, such radios do not function.

In some cases, the radio may not work due to a problem with your vehicle’s electrical system, such as a blown fuse.

If your car radio won’t turn on, and you know you have the correct code, the issue may be with the battery itself or damaged other electrical equipment, such as the ignition switch.

Also, if your battery is more than three years old, it’s probably time to replace it.

A weak or dying battery can cause all sorts of electrical problems in your car, including making your radio behave strangely.

Why Is Car Radio Dead After Replacing Battery?

In many cases, a car radio is dead after replacing the battery because of the anti-theft protection and needed code.

It’s important to enter the code correctly so that your radio does not become disabled.

If you’re having trouble finding the code, try these tips:

#1. Use the owner’s manual. The owner’s manual will have the correct code for your radio.

#2. Look for the sticker. Many radios have a sticker on them that has the code.

#3. Call the dealership. If you can’t find the code, you can always call the dealership, and they should be able to give you the code based on the VIN and radio model.

If you cannot enter the code or after entering the code the radio still doesn’t work, try these tips:

#1. Check the fuse. A blown fuse can cause your radio not to work.

#2. Check the electrical system. A problem with the electrical system can also cause your radio not to work.

#3. Check the battery. If your battery is low or flat, it will not provide enough current to run the radio.

Why Car Stereo Won’t Turn On But Has Power?

If your car stereo won’t turn on, but it has power, it may be because of a problem with the ignition switch.

The ignition switch is what turns on the radio when you turn on the car. If the switch is damaged or not working properly, it can prevent the radio from turning on.

Another possibility is a problem with the wiring between the radio and the ignition switch. This can be caused by a loose connection, a short circuit, or a damaged wire.

Since the radio has a power fuse should be OK, but some radios have built-in fuses, typically located on the back side, and some additional in-line fuses located on the power wires.

If any of the fuses are blown, that may be why your car radio won’t turn on, so check the fuses and make sure they have the correct amperage.

How to Reset Car Radio After Changing the Battery?

Resetting the car radio after replacing the battery depends on the car and radio model installed.

In most cases, the radio will reset itself when disconnected from the battery, but you can also reset it manually by pressing a reset button or holding down a key combination on the radio.

In most car radios, after resetting the radio, you have to enter the code. 

The code is usually located in the owner’s manual, on a sticker on the radio, or you can ask the car dealer for the radio code.

If your car radio is still not working after replacing the battery and resetting it, there may be a problem with the electrical system of your vehicle. 

Why Is Toyota Radio Not Working After Battery Change?

Toyota radios have an anti-theft feature that kicks in when the battery is disconnected.

To reset the radio and make it work after the battery change, you need a four-digit code that is specific to your Toyota.

With code in hand, you can reset the Toyota radio by following the few steps below:

#1. Turn the ignition on so that only accessories are powered. When the power is ON, you should see the letters SEC displayed on the screen.

#2. Hold the TUNE ^ button and the 1 button at the same time until three lines appear.

#3. Use the 1 button, and press until the first digit of the code appears. 

After the first press, you will see the number zero on the screen. After the second press number TWO will appear, and so on.

#4. Press button 2 until the second digit of the code appears.

#5. Press button 3 until the third digit of the code appears.

#6. Hold the SCAN button until SEC appears on display and disappears.

Toyota radios allow you to make 10 attempts to enter the code, and after that, you have to take the radio to the dealer so they can unlock it for you.

Why Is Mercedes Radio Not Working After Battery Change?

Mercedes radios have an anti-theft feature that blocks the radio after disconnecting it from the battery. To activate the radio, you need to enter the four or five-digit code (depending on the radio model).

In the same way as for other cars, You can find the code for Mercedes radio in the owner’s manual or get it from the dealership.

To reset the radio and turn it on after the battery change, follow the steps below:

#1. Check and replace if needed, the main radio fuse under the bonnet.

#2. Check and replace if needed, the anti-thief fuse in the trunk.

#3. Turn the ignition on.

#4. On the radio screen, the word CODE will appear.

#5. Enter 4 digit or 5 digit code using a radio keypad.

#6. After entering the correct code, the word OK will appear in the lower right corner.

#7. Press the button under the word OK, and the radio will turn on.


Your car radio may not turn on after you replace its battery if you have a damaged fuse, a locked radio, or an improperly installed battery. Damaged fuses are common in car radios, while radio damage occurs from improper installation or electrical surges. Meanwhile, a locked radio happens when your car’s memory resets itself.

Sometimes, you can fix your car radio issue with ease. However, you may need to take more complex steps to turn on your radio if the damage is a bit more complicated than usual.