Can A Bad Alternator Cause Limp Mode?

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A lot of things can happen to a car when the alternator goes bad, such as your stalling, hard starting, battery dying, etc. But can a bad alternator cause limp mode?

The simple answer is yes, a bad alternator can cause limp mode due to several reasons which we will explain in this article.

It’s worth noting that there are other things that can cause limp mode in a car, so it’s important to consult with your mechanic to ensure the problem is truly from the alternator.

What is an Alternator?

Also known as dynamo-electric machine, the alternator is an important component of a car. It helps in charging the battery and converting mechanical energy from the engine into electrical energy to turn on all equipment inside your vehicle.

The alternation process occurs when you drive by pushing down the gas pedal which rotates an electric brush that then turns a shaft.

The spinning turns the rotor which is composed of copper wire that’s wound in coils and with stationary magnets on top. When this happens, the output voltage increases from 12 volts to 14-15 volts (depending on your car).

You can also increase alternation process by rotating engine faster or adding more windings but it will make your car heavier.

How Can You Tell If There’s A Problem With The Alternator?

According to the car experts at AutoZone, there are a few ways. One way is by looking for warning lights on your dashboard.

Basically, if you see that the Check Engine light or Service Engine Soon light has come on then this probably means that something with engine performance such as fuel injection problems or an alternator problem could be causing it.

Another way is to take the car in for a quick diagnostic test. This will tell you if there’s an alternator problem, and whether or not it needs to be replaced.

Can A Bad Alternator Cause Limp Mode?

Can A Bad Alternator Cause Limp Mode

Yes, one of the most common causes for a car to enter limp mode is due to a bad alternator. When an alternator goes out, it can cause the voltage in your vehicle’s electrical system to drop below what is needed by many electronic components.

This includes things like headlights and windshield wipers which require 12 volts instead of 14, and the engine control unit which needs 14 volts.

When these components don’t get enough voltage to function, they will enter limp mode until one or more of them is replaced with a working item.

If your alternator has gone bad, it may be easy to identify as you’ll likely see an illuminated check engine light on your dashboard.

Mechanics may also be able to diagnose a bad alternator by listening for the clicking sound that is often associated with an out-of-warranty or worn-down part.

If you’ve noticed your vehicle entering limp mode, it wouldn’t hurt to have one of our mechanics give your car a once over or ask them to diagnose the problem for you.

What Does A Bad Alternator Sound Like?

If your car is constantly going louder and quieter, it could be a sign of a bad alternator.

A bad alternator can also make the car to produce small rattling or grinding sound when the engine is running.


Can a bad alternator cause limp mode? Yes! As we’ve answered before, it is possible that a bad alternator can cause limp mode in your car, but it’s not likely as there are other components which require 14 volts.

If your alternator has gone bad and you notice an illuminated check engine light on your dashboard or clicking sound when starting your car, it’s best to get your alternator repaired as soon as possible.

If it’s not something you can do, the wisest thing is to reach out to your auto mechanic for repairs.

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