Car Fuse Keeps Blowing – Possible Reasons and Fixes

Car fuses can blow due to the wrong fuse, battery issues, bending fatigue, faulty alternator, high resistance, rust/corroded fuse terminals. In addition, fuses can malfunction if placed incorrectly after a car accident or after a repair. If you diagnose and replace it correctly, this can be avoided.

Are you frustrated with your car’s constant fuse blowing? You’re not alone. This can be a frustrating and a potentially dangerous problem. Fear not, understanding the causes and how to fix it will save you both time and money. 

So, why does the car fuse keeps blowing

Now, let’s discuss the causes of why your car’s fuse keeps blowing. 

Why Does Car Fuse Keeps Blowing?

Car fuses are one of the car’s most important components that ensure the vehicle’s electrical connection safety. Several factors can cause a car fuse to blow. Some of the most common reasons are given below: 

Reason 1: Wrong Fuse

The first and the most common reason for a blown fuse is the use of a wrong fuse. If the fuse you are using has malfunctioned in terms of its material or electric circuit or has an incorrect ampere rating with respect to its application. Then it’s likely to be blown. It’s because the fuse will be unable to handle the current flow. 

Solution: Always refer to the user manual provided with your vehicle to find the correct fuse and amp rating. Fuse diagrams are often attached to the fuse box cover in some cars. Match the diagram’s color pattern and ampere rating.

Reason 2: Battery Issue

The normal battery should have a voltage between 12.5 to 12.9 volts when the car is off. With the engine running your car battery voltage should be higher than 12.9 volts and should be about 13.5 to 14.5 volts.

Anything below that voltage means the battery is weak. A weak battery can cause the car electric fuse to blow if the voltage drops below the minimum threshold that is needed to properly operate the electrical system. 

Low voltage can increase the electrical load on the alternator. As a result, the electrical system will overload and cause the fuse to blow as a protective measure. Moreover, a weak battery may not be able to deliver the required current to start the engine, and the starter motor may overheat and blow a fuse.

Solution: Ensure that the battery is in good condition, you can check the battery’s condition using a multimeter. Also, perform a load test to see if the battery can hold its charge. The fuse-blowing issue won’t be fixed until the battery is fixed.

Reason 4: Wire Damage

Another reason is wire damage due to bending fatigue of the electric circuit wirings. Bending fatigue is a type of mechanical failure, it happens when a material is repeatedly bent, causing it to weaken and eventually fail. If the wires are repeatedly bent, it can cause wear over time.

Bending fatigue can occur in places like your car door, doors are frequently opened and closed. Damaged/frayed wires are susceptible to bending fatigue leading your car’s door lock fuse to blow. Additionally, it compromises the security of your car. 

Solution: Use a wiring harness if needed to adjust the wires correctly to prevent bending the wires. Check the condition of the wires, if you see any visible damage consider replacing them. You should also use wires that the manufacturer recommends. Heavy-duty wires are durable, long-lasting, and less likely to bend.

Reason 5: Faulty Alternator

Alternator is responsible for charging the battery in the car. Faulty alternators can cause sudden surges or fluctuation of power, resulting in blown fuses. If the alternator has a faulty voltage regulator or have an internal short ciruict it cause the fuse to blow. Then until the alternator issue is fixed, it will cause the fuse to keep blowing again and again.

Solution: Inspect the alternator for defects, there might be an issue with the alternator’s output. You can easily test the alternator by yourself with a multimeter. Alternator voltage should be 1/1.5 or up to 2 volts higher than battery voltage.(1) For instance, if your car battery is 12V, the ideal alternator voltage should be around 13.5V or up to 14V.

Reason 6: High Resistance

Another crucial reason behind your car fuse keeps blowing is the high resistance within the fuse. When the fuse gets overloaded by excess current flow, it will generate heat. If a fuse experiences internal issues, whether due to aging or manufacturing defects, it can result in increased resistance. 

This increase in resistance generates heat that can cause the fuse to blow.There may be a manufacturing defect, an old fuse, or any physical problem. Similarly, if the supply or demand load goes beyond the fuse limit, high heat can cause the fuse to blow, thereby protecting the entire electrical circuit from complete damage.

Solution: Inspect the source of the issue by diagnosing the electric component of the blown fuse. If the component doesn’t have any malfunction then diagnose the fuse with a multimeter, if the resistance is greater than the specified resistance, replace it.

Reason  7: Rust/Corrosion

Rust/corrosion are the enemies of any automobile parts since it greatly damages the components. Fuses may capture moisture from the environment and become corroded, disrupting the electricity flow and end up getting blown.

Solution: Always perform routine maintenance of your vehicle, if the fuse has corrosion, replace it accordingly. You can spray vinegar on the fuse’s corroded parts. After 24 hours, use a brush to remove the corrosion gently. 

Car AC Fuse Keeps Blowing

Your car’s AC fuse can get blown if the wiring harness is damaged due to a bad field coil, faulty compressor clutch, bad wiring harness, and faulty AC pressure switch. Thoroughly diagnose what’s causing the issue and do replacements as necessary.

Car Cigarette Lighter Fuse Keeps Blowing

The most common reason behind the cigarette lighter fuse keeps blowing is having foreign objects like metal or any other objects in circuit. Cigarette lighter fuses can also blow due to corroded or damaged components. Check the fuse and replace accordingly. 

For example, if the fuse is designed for a 15 amp capacity, it’ll blow if the circuit draws more than 15 amps. Learn details about the cigarette lighter fuse blown issues.

Car Radio Fuse Keeps Blowing

Car radio fuse can keep blowing for the following reasons:

  1. You’ve installed the wrong fuse.
  2. The connection is Incorrectly grounded.
  3. There’s a voltage overload in the circuit. 
  4. The system has defective or thin wiring.

Also, If the stereo system has a malfunctioned part, it can cause overload in the circuit, drawing more current and eventually blowing a fuse.

Solution: Ensure that the fuse installed in the radio system has the correct amp ratings. Check the user manual for a fuse chart where you’ll find the ideal amp ratings. Perform a visual inspection for physical damage to the components. Additionally, you can diagnose the circuit for a voltage overload by using a multimeter.

Car Horn Fuse Keeps Blowing

The common problem with car horns is the ground connection that the horn attaches to. When the bolt connecting the ground becomes rusty, it can draw excessive amperage, leading to the blowing of the fuse. Also, Over time, debris can accumulate in the horn, causing the coil to overheat and ultimately resulting in the burnout of the horn.

Solution: The first step in resolving this issue is to clean the contact. If the fuse continues to blow, the horn relay or the horn itself may be faulty. In that case, replace the horn or the horn relay accordingly. 

The typical price range for replacing a horn relay is from $53 to $61. The estimated labor cost is between $31 and $39, while the parts cost around $22. Also, the horn replacement costs between $145 and $163 on average, including $75 for parts, and 70$ to $89 is the labor cost.

Car Light Fuse Keeps Blowing

Your car’s headlights or tail lights/brake lights fuse can keep blowing if one of the lights has a malfunction. Other reasons include using a wrong fuse with an incorrect amp rating, having corrosion in the fuse or voltage overload in the circuit. 

Solution: To identify the problem’s source, start with the lights. Remove all the lights, install them one by one, and turn them on to see which causes the fuse to blow. If all the lights seem to be working fine, then inspect the wirings and the circuit for overload. Get the help of a mechanic who can thoroughly diagnose the circuit for you.

Car Starter Fuse Keeps Blowing

Your car’s starter fuse can keep blowing for the following reasons:

  • Ancillary problems: Issues with your car’s ancillary parts, like the fuel pump, cooling fans, and window motor, can cause the fuse to blow.
  • Overheating engine: Overheating the engine can cause high resistance in the starter motor circuit, leading to an increase in the current draw through the starter fuse. This can cause the fuse to blow.
  • Wiring issues: Damaged/burnt/frayed wires can disrupt the normal electrical flow to the circuits. It can also overload the circuit drawing more current to the point where the fuse gets blown.
  • Faulty relay: The relay circulates the voltage between the starter and the battery by opening and closing the circuit when needed. A faulty relay is another cause of a blown fuse. Normally, relays last about 50,000 cycles. 

Car Battery Charger Fuse Keeps Blowing

Constant fuse blowing of your car’s battery charger indicates excessive current overload into the circuit. This may be due to a short within the charger or an inability of the charger to provide constant current for charging the battery, causing an overload or fluctuation.

Another reason could be the charger leads are accidentally connected to the wrong battery terminals (negative cable to the positive terminal and positive cable to the negative terminal). This could cause the fuse to blow and damage the battery.

Other reasons include a short circuit, a faulty battery or short in one of the cells of the battery, and a faulty car battery charger. Now, let’s check out the solutions to this.

Solution: Confirm that the positive lead (red) of the charger is connected to the (+) battery post and the negative lead ( black) to the (-) post to avoid reverse polarity. Replace the charger fuse with one of the same amp ratings and check if it blows again.

Car AMP Fuse Keeps Blowing

Some people have reportedly faced the 15 Amp, 20 Amp, and 40 amp car fuse blowing issues. It primarily happens if you install an incorrect fuse to the circuit. If one of the components needs a 20 amp fuse, you shouldn’t install any higher or lower amps than that. 

The system won’t be damaged by installing a lower amp fuse because there will be no overcurrent issue. Still, it leads to frequent power interruptions and inconvenience from having to replace or reset the fuse frequently. Alternatively,  If you use a fuse with the wrong amperage, the fuse could not blow during overload, damaging the circuit.

Car Fuse Keeps Blowing After Car Damage/Repair

If the car fuse keeps blowing after a damage or a repair, something may have messed up. Get the help of an expert to diagnose what’s causing the issue and take necessary steps to fix it. It could be one of the problems I’ve discussed above. Now, let’s discuss how to prevent the car fuse from getting blown.

Car Fuse Keeps Blowing: How to Fix?

The fuse box location may vary depending on the vehicle type and model. Follow the user manual for the exact fuse location and fuse diagram. Here are the general steps to replace a blown-out brake fuse as follows.

Tools Required

  1. Fuse puller.
  2. New fuse.

Now, follow the below steps thoroughly in the correct order.

  1. Locate the fuse box
  2. Identify the blown-out fuse
  3. Remove the blown fuse
  4. Replace the fuse
  5. Finally, test the fuse.

By following the above steps, you can easily replace the brake light fuse on your own at home. You might be wondering if you can remove the fuse with the battery still connected. The answer is no, before opening or working on a fuse box, turn off your vehicle’s ignition and disconnect the battery.

How Much Does It Cost To Replace a Car Fuse?

The cost of fixing a car fuse can vary but generally ranges from $110 to $140. This includes the cost of the fuse itself, which can be between $10 to $20, and labour costs for a professional to replace the fuse. In general, labour costs range between $65 and $100 per hour, depending on the shop.


How Long Do Car Fuses Last?

Generally, car fuses can last the entire car life. However, many car manufacturers recommend replacing the fuses every ten years. Meanwhile, it’s also recommended to perform routine maintenance checkups. Refer to your car’s user manual for more details about how to replace a fuse.

Can A Blown Fuse Stop a Car While Driving?

Yes, If the ECU, fuel pump, and ignition fuse gets blown, the engine units will lose power and the car will stop after driving for a while. These critical sensors need to function properly to keep the car going by running the engine continuously. If one of the sensors blows, it can cause the engine to shut down, stopping the car while driving. 

Is It Safe To Replace All Fuses In A Car?

Yes, replacing all the fuses in a car can be a safe and effective way to troubleshoot electrical issues. However, it is important to remember that not all fuses are interchangeable and that the correct type must be used for the job. Additionally, it is recommended to refer to the car’s owner’s manual or a professional mechanic before making any repairs.


That was everything on your query on why the car fuse keeps blowing. Hopefully, you’ve got the answers to why this happens and how to prevent it in the future. In order to replace fuses correctly, always refer to the user manual and the fuse type/amp rating.

Consult an expert if you are not confident about the procedure. Goodbye, see you later.

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William Baldwin

This Is William Baldwin, The Founder & Managing Editor of this website. Me and my team share automotive tips, tricks, and news

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Talha Atta

Talha Atta, a Mechanical Engineer and experienced technical content writer and editor at with a passion for the automotive industry.