Ford Fiesta Aux Input Is Not Working—Why And What To Do?

Do you have a new Ford Fiesta, but you can’t seem to make the aux input play music from your phone, and you want to know what is wrong and how to fix the problem? You’ve come to the right place, for we have researched this question and have the answer for you.

Check the cable that connects your device to the aux input for damage and replace it if you find any. Check the fuses for the car audio of your Ford Fiesta and replace any that are no longer working. Other possible causes include:

  • Speaker problem
  • SYNC issues

Learn more about the aux input in your Ford Fiesta in the succeeding sections. We also included solutions for the causes below.

Read on!

Rear view of black Ford fiesta parked in the street, Ford Fiesta Aux Input Is Not Working—Why And What To Do?

What is an aux input?

The aux input or the auxiliary input is a universal asynchronous audio port that is present in most audio devices, from car head units to home theatre systems and concert audio systems.

Let’s break down the information in that long sentence.

It is called an “input” because the movement of data comes from a third-party device like your phone, a tablet, a CD player, or a Walkman. This information goes into the head unit of your Fiesta. It is an “input” because this movement of information cannot happen in reverse.

It is a universal port because of the type of connector you can use. You can access the aux input using a 3.5 mm jack—the same one your earphones use. It is the same jack that you will find in thousands of other devices that you can use in any other device.

If it has a 3.5 mm input plug, it will work with your device.

It is asynchronous because your head unit is independent of whatever happens in the device that is sending it music. Since the head unit doesn’t care how your device processes the music, it doesn’t have to make sure that your device receives the electrical energy that it needs. Thus, you can’t charge with the aux input.

Moreover, being asynchronous means that the audio output that goes to your head unit will not contain any other information. This means that your head unit will not be able to display any musical graphs or music visualizations coming from the music that is playing.

How An Aux Input Works

The audio processing happens in the device that is playing the music. If you’re using a CD player, the CD player will be in charge of processing the information from a CD and converting that information into music. If you’re using a tablet, the app on your tablet is in charge of processing the data inside the audio file and playing it as music.

Part of the data processing is signal processing. Any digital audio is converted into analog audio before it is transferred through the cable to your head unit. Your head unit doesn’t do any signal or data processing.

The music that the device plays is sent to your aux input in real-time bits. This means that no buffering is happening while the music is moving from the audio device to your head unit. Thus, if there is an interruption in the processing, there will be a corresponding real-time interruption of the music on your head unit.

What the head unit does is amplify the audio input before it goes out to the speakers.

Disadvantages Of Aux Input

The major disadvantage of aux input is the source.

This may come as a surprise, so let’s talk more about this below.

The app that plays music for your phone is optimized to output that music to earphones with audio drivers (another name for speaker inside earphones) that are smaller than the holes of human ears.

However, when you send that music through the aux input and to your head unit, you will be playing the music through large speakers inside your Ford Fiesta. The difference in speaker size translates to how much audio detail is present in the audio.

Thus, the music you get from mobile phones is not always high-quality.

Improving Aux Audio

Modified 2015 Ford Fiesta sound system speakers and Jack Daniel's whiskey mini bar at Manila International Auto

This is not the end of aux input audio. There are ways to improve the audio output through the aux input, like using an equalizer.

An audio equalizer is a filter that separates certain sound frequencies. This separation allows you to boost or lower these frequencies independently. Mixing the settings of an equalizer will help improve the sound output of your music.

An equalizer can be an app on your phone, a built-in feature of your music player, or third-party hardware that processes the music output of your head unit before it reaches the speakers.

The Clarion EQS755 car audio equalizer is available on Amazon through this link.

How to fix aux input problems?

Simple 1 8 inch small jack cable connector aux input on an audio device

Now that you have a better understanding of how the aux input works in your Ford Fiesta, you will be able to understand the possible causes of the problem.

Cable Problem

The most common cause of the problem is a failing cable.

The transfer of data is in real-time. This means that any interruption cannot be mitigated by buffers created by your head unit simply because there are no buffers. Any problems with the cable will impact the music in real time.

If the problem is the audio cable, the head unit will have power but will not have any audio output, or the audio output is of very bad quality. A bad aux cable sometimes will cause the audio level to become too low. Another symptom of a bad cable is a sound output that sounds rough or grounded.

You can resolve this issue by replacing the audio cable.

A 3.5mm aux cable from KabelDirekt is available on Amazon through this link.

Fuse Problem

The fuses in your Ford Fiesta are responsible for protecting the wiring and the electrical components—including the head unit—from damage due to a surge of electricity.

A sudden surge of electricity will cause the filament inside the fuse to break. Once broken, the electrical current that passes through the fuse will no longer reach the head unit.

The head unit will not have any power if this is the cause of the problem.

Replace the fuse with one that has the same ampere rating. Never use one that has a different ampere rating because that can cause the wiring to burn out. This is an even bigger and more expensive problem to fix.

The CrocSee car fuse kit is available on Amazon through this link.

How to troubleshoot speaker problems in Ford Fiesta?

Profile view of red ford fiesta parked in the street

A speaker problem can range from music output with static to no sound.

Troubleshooting a possible speaker problem is easy. Check all sound and music sources on your head unit. If you get the same sound quality regardless of the music source, then the problem is likely the speakers.

Unfortunately, the only solution to a speaker problem is a replacement. You can replace the speakers yourself or by having a mechanic do the replacement for you.

A pair of JBL GTO 629 car speakers are available on Amazon through this link.

How to troubleshoot SYNC issues on your Ford Fiesta?

A Ford Fiesta ST parked in front of an abandoned building

SYNC is a software system that runs most electronic devices in newer Ford vehicles like the Fiesta.

It is an operating system that takes control of many electronic devices in your Fiesta, like navigation, entertainment, and driving information. It provides you with voice control over these systems and more.

A problem with the SYNC system can prevent your aux input from working. SYNC can freeze and render your entertainment system inoperable. This can seem like the aux input is not working if you were playing music through the aux input when SYNC had a problem.

How to fix a frozen SYNC system?

Resetting your SYNC system will fix a frozen SYNC. Choose the instructions that correspond to the system that you have.

If a regular reset does not fix the problem, you must do a master reset.

Resetting Systems With A Power Button

  1. Press and hold the “Power” and “seek right” buttons.
  2. Wait for 10 seconds or so while holding the buttons down.

Resetting Systems Without A Power Button

  1. Press the “volume down” and “seek right” on the steering wheel controls.
  2. Wait for 10 seconds or so while holding the buttons down.

How to do a SYNC 4 Master Reset?

A SYNC Master Reset is similar to a factory reset where the SYNC system reverts to the state when it just left the factory. Keep in mind that doing a SYNC Master Reset will erase all your data. This includes subscriptions, Connected Navigation, call history, text messages, previous Bluetooth pairings, and BlueCruise.

Subscriptions can be frozen for up to 10 days after a SYNC Master Reset.

If you still want to do a SYNC Master Reset, follow the steps below:

  1. Go to the “Settings” icon on your Fiesta’s SYNC screen.
  2. Tap “Reset.”
  3. Choose “Master Reset.”
  4. Accept the prompts on the screen and wait for the reset to complete.


Rear view of black Ford fiesta parked in the street

Check each of the possible reasons why the aux input in your Ford Fiesta is not working to fix the issue. Go through each of the possible causes until you get to the culprit.

If you enjoyed reading this article, you might find the articles below equally enjoyable to read:

Why Won’t My Ford Fiesta Start?

How Much Does a Ford Fiesta Weigh? [Manual vs. Automatic Discussed]

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