Can A Bad Alternator Cause A Misfire? All You Need to Know

Can A Bad Alternator Cause A Misfire? This is a question that is often asked by car owners who are experiencing engine misfire.

In this article, we will explore the relationship between a bad alternator and a misfire. We will discuss the signs of a bad alternator and how to identify if the alternator is the cause of misfire.

So, if you are experiencing a misfire in your car and you suspect that your alternator may be to blame, keep reading to find out everything you need to know about this topic. Can A Bad Alternator Cause A Misfire? Let’s find out.

How Does The Alternator Work?

The alternator plays a vital role in the car’s electrical system by keeping the battery charged and ensuring that all electrical components function correctly.

If the alternator fails to work, the battery will run down quickly, and the electrical system will cease to operate properly. It is essential to have a functioning alternator for the smooth functioning of your car’s electrical system.

The alternator is made up of three main parts: the rotor, armature, and housing. When the external voltage regulator applies current to the brushes, the rotor spins inside the housing, generating electricity that passes through the armature and back into the battery or directly to other components. The question arises, can a bad alternator cause a misfire?

Can A Bad Alternator Cause A Misfire?

When a car’s engine misfires, many car owners think it’s due to faulty spark plugs or clogged fuel injectors. But can a bad alternator cause a misfire?

In general, a bad alternator does not have a direct impact on engine performance. The alternator’s primary function is to generate and provide electrical power to the car’s electrical system. Hence, it is less likely that an engine misfire issue could arise from an alternator issue.

Nevertheless, there are certain situations where the alternator could be a contributing factor to an engine misfire. If the alternator malfunctions, it can cause the engine’s spark plugs to fail. The spark plugs require electricity from the alternator to create a spark, which is essential for ignition.

If the alternator fails to generate sufficient electrical current, it will result in an engine misfire. However, this scenario is not very common.

Therefore, before pointing fingers at the alternator, car owners should check for other possible causes of engine misfires. If none of the usual culprits, such as bad spark plugs or clogged fuel injectors, are the root cause of the issue, then checking the alternator’s condition is crucial.

Signs Of a Broken Alternator

The alternator is a critical component of a car’s electrical system. When the alternator is not functioning correctly, it can cause various problems, such as a dead battery, dimming lights, and electrical failure. Therefore, it’s crucial to be aware of the signs of a broken alternator to avoid potential issues.

Here are some possible signs of a broken alternator:

  1. Dead battery: The alternator is responsible for charging the battery. If the alternator is faulty, the battery will not charge, and the car may not start, or the battery will die.
  2. Dimming lights: The alternator also powers the car’s lights. When the alternator is not working correctly, the lights may flicker, dim or turn off.
  3. Warning light: If the alternator warning light appears on the dashboard, it indicates that the alternator is not working correctly.
  4. Electrical issues: The alternator powers other electrical components in the car, such as the radio, air conditioning, and power windows. If the alternator is not functioning correctly, these electrical components may not work or may work inconsistently.


How To Identify If The Alternator Is The Cause Of Misfire

If you are experiencing engine misfire, there is a possibility that it is caused by a faulty alternator. While it is not a common cause of engine misfire, it is still essential to identify if your alternator is the culprit, especially if other components have been ruled out

Battery Warning Light

The first sign that you should look out for is the battery warning light on your dashboard. When the voltage output of your alternator falls below a certain level, usually below 13 volts, your battery warning light will be triggered, indicating low battery levels. A working alternator should output between 13 to 14.5 volts.

If your alternator is not producing enough voltage, your engine may require more electric current to power the spark plug, leading to a misfire. The battery warning light is an early warning sign that your alternator is starting to fail, and you need to address the issue as soon as possible.

Check Engine Light Is Also On

If your check engine light is also on, it could be a sign that your alternator is failing. The alternator powers a large part of your vehicle, including your engine, and when it fails, it can trigger the check engine light.

Manufacturers have taken it upon themselves to notify drivers through different means, and in recent cars, the warning light will be accompanied by a warning message. A bad alternator can cause your engine to misfire, among other problems, and it’s crucial to address the issue as soon as possible.

Check The Alternator Belt

A worn or loose alternator belt can cause the alternator to malfunction. Inspect the belt for any signs of wear or looseness. If the belt is damaged or loose, it needs to be replaced.

Inspect The Alternator Wiring

Check the alternator wiring for any signs of damage, such as fraying or corrosion. Damaged wiring can cause the alternator to malfunction.

How To Test A Faulty Alternator

Testing your car’s alternator can help you diagnose any problems it might have before it fails completely.

Test With Multimeter

One of the simplest ways to test an alternator is by using a multimeter. A multimeter is a common handheld tool used to measure the voltage on electrical devices and test electrical connections. To test the alternator with a multimeter, you will need to start by turning off your vehicle and disconnecting the battery. This step is essential to prevent any accidents and ensure your safety.

Next, locate the alternator and use a wrench or sockets to remove any necessary components that block access to it.

Check for any visible signs of damage, such as worn-out belts, cracks, or corrosion. Once you have access to the alternator, place the multimeter probes on the battery terminals, ensuring that the positive probe is connected to the positive terminal and the negative probe to the negative terminal.

Check the multimeter reading. Under normal circumstances, the multimeter should read between 12 to 13 volts. If the reading is lower, it means that the alternator is not charging the battery. Turn on the vehicle and test the voltage again.

Within few seconds, the multimeter reading should increase. If it does not, it means that the alternator is not working correctly, and you should replace it immediately.

You can also load the battery by turning on the heater, radio, and other electrical components. Test the battery again, and if the reading drops, it means that the alternator cannot handle the vehicle’s electrical demands and is faulty.

Test With Scanner

Another way to test your alternator is to scan for codes related to the alternator with an OBD scanner.

An OBD scanner is a device that connects to your vehicle’s onboard computer system and retrieves information about its performance. To test the alternator with an OBD scanner, you will need to plug it into your car’s OBD port and follow the manufacturer’s instructions.

The scanner will display any codes related to the alternator, such as low voltage or high voltage, which will help you determine whether it is functioning correctly or not.

What Else Could Cause My Car To Misfire?

If your car is misfiring, there could be various reasons behind it. Apart from a faulty alternator, which we’ve already ruled out, some other common reasons include a bad fuel injector, defective vacuum seal, faulty exhaust-gas circulation, bad spark plugs, and issues with the ignition system.

Bad Fuel Injector

A bad fuel injector can result in a lean fuel-to-air mixture, leading to the larger volume of air in the combustion chamber. This can cause a misfire as the air-to-fuel ratio is not optimal.

Defective Vacuum Seal

Similarly, a defective vacuum seal can lead to decompression in the chamber, causing problems with the combustion process and resulting in misfire.

Issues With The Exhaust-Gas Circulation

Issues with the exhaust-gas circulation can also cause problems with the sensors in your car, resulting in a misfire.

Faulty Spark Plugs

Faulty spark plugs can collect deposits and not fire at full strength, leading to misfires. Replacement cost for a full set of spark plugs typically ranges from $200 to $450.

Apart from spark plugs, coils, onboard sensors, and related circuitry also play a role in the ignition system. If any of these parts fail, it could cause a misfire. However, the alternator is not a likely cause of a misfire. While it can cause other electrical components to malfunction, it is not directly responsible for a misfire.

Low Fuel Pressure

Low fuel pressure can also cause a misfire, as there won’t be enough fuel to start the vehicle. Low compression in the engine cylinder can also lead to a misfire.

When there is insufficient compression due to a disruption in the mixture of air and fuel, combustion cannot occur properly, leading to misfires.

The cost of fixing a misfire can vary depending on the severity and the underlying cause of the issue. Clogged fuel injectors and bad spark plugs can be fixed for anywhere between $200 and $1500, depending on the type and degree of the fault in the engine


In the previous article, we discussed can a bad alternator cause a misfire in a car’s engine. We also went over the signs of a broken alternator and how to identify if the alternator is the cause of a misfire.

Additionally, we explained how to test a faulty alternator using a multimeter and provided steps for this testing process. In summary, a bad alternator can indeed cause a misfire in a car, and it’s crucial to diagnose and replace a faulty alternator to prevent further damage to the vehicle.