Subwoofer on non Bose A4 not working

[A4B8R9M]

dear all,

I have 2009 a4 1.8tfsi se. I have just been in the car and I adjusted the subwoofer volume, but sound isn't changing. I checked the factory sub in the boot compartment and it isn't working. What can I do?

I tried taking the cable off and putting it back in but that didn't work. Anything else? Any help will be appreciated.

 

[kev.s]

could be your amp, i had to get mine change on the B&O system, and the car only 2month old!!

 

[A4B8R9M]

How do I check this? Or fix it ?

 

[kev.s]

no idea sorry, i gave the car to audi, thats what they told me, but my volume on the radio was pulsating, like turning volume up and down constantly.