Why My Stereo Won’t Play On Both Speakers Via AUX?

Aux Cable

There are serval reasons why your stereo won’t play on both speakers via AUX, such as a broken AUX Cable, Phone or Stereo formatting, and issues with the physical connection to the speakers. You should troubleshoot your way of finding which of the components are not working correctly. 

If the stereo alone allows both speakers to play, then the issue does not lie in the communication between them.

However, if you use the aux to connect to an external device as the source, then it most probably means that something is wrong between the external source and how the stereo is connected through the cord or the input.

There could be several other reasons why your aux could not deliver audio outputs to two speakers.

Trial and error would likely be necessary, but here’s a list of possible causes of the problem and how you can troubleshoot it.

The device is not set up correctly

If the settings are accessible for you, make sure whichever device you connect the aux to enables the left and right speakers to produce sound, because not all of them automatically allows it. 

For example, for a laptop-to-stereo connection, you can go to the computer’s sound playback properties and set the balance equally to make the sound come out of both channels.

Chain of the problem

You should aim to work through the problem, starting from the source. In this instance, you would ideally start from the source like your Mobile Phone or Laptop → Aux Cable → Stereo or Head Unit → Wiring to Speaker → Speakers themselves.  


Aux to speakers diagram
Diagram of potential components that could be faulty, installed, or formatted wrong.


Physical Issues and Defects

These are the most common and straightforward causes. 

  • In terms of tangible issues, the most straightforward recommendation you’d get is to clean your components: blowing into your ports to get rid of dust that could obstruct the signal or cleaning the jack with a wet wipe and a toothpick.
  • It could be that either your cord, aux input or source is defective. Try swapping out your cable. 
  • The cable might not be plugged in snugly. Also, try to push or twist the plug around the input. If you wiggle it around and get short and quick sounds from the idle speaker, the aux input itself might be the problem.
  • Electronically speaking, if other types of external sources (e.g. devices or gadgets) or modes on the stereo (e.g. radio, CD) allows both speakers to function, then the internal switching of the source could be malfunctioning.


One or some of the components may not be suitable for the others. 

Switch them to different ones to identify which one has an issue. 

  • Use another cord to see if it changes anything. If it doesn’t, then you’ve narrowed the points of observation down to just the stereo’s aux input and your device’s output. 
  • Repeat the process with the input and source, if possible, until you can recognize one root cause.


Wrong Type of Plug/Incorrect Connections

The type of jack or plug can be determined by the number of rings or black stripes. For instance, a stereo plug has one more metal ring than a mono one.

Interchanging them usually would not cause an issue, but it could if a circuit is old or poorly designed.

That said, using a stereo jack with a mono plug shorts your right channel to ground at the source, leaving you with a left channel only. 

Similarly, a stereo socket and a mono jack combination will allow you only to get sound from your left channel.

If this is the case, one solution is to use an adapter to avoid the shorting.

Final Thoughts

Like most problems, the best way to solve the problem is to work your way through the possible components causing the issue and check them off as you go to narrow down the source of the problem. 

  1. Define the problem
  2. List possible issue components  
  3. Evaluate and rank them
  4. Methodically work through them, preferable starting from the source.
I loved my car but was frustrated with my media system. So I upgraded my stereo, making silly wires and precarious phone mounts a thing of the past. The Apple Car Play stereo was so good I wanted to show more people how this could be done and truly upgrade their cars multimedia system! Founder StereoUpgrade.com
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