Christianswe26

Hi all!

I have an Audi S3 8P 2009 that has a serious battery drain problem. The battery drains overnight causing the car to not start without jump starter.
When reading how much ampere it drains from the battery after having locked the car it reads about 1.2 Amps. Another thing that happens during this is that the red hazzard light in dash is staying on. Sometimes it can go out for a minute or so but then illuiminate again.

There is 2 fuses that seems to be the cause of this, when pulling out the 2 fuses there is no longer any battery drain and the hazzard light button turns off after locking the car and when the can-bus has "shut down". The fuses are F19 and F20 in the engine compartment next to the car battery.

Have anyone else had this same issue and what was the cause of it? I'm thinking it might be the amplifier that might cause this due to the heavy amp drainage as my car has a full BOSE sound system. What do you think?

Best regards,
Christian

findalex

Can you narrow it down to one of the fuses? That will allow you to isolate which electric circuit is causing the drain. If your car is stock, then your sound system won't drain the battery after you turn off the car.

The cigarette lighters/power plugs are always on in the A3 even when the keys are pulled out. Do you have a cell phone charger or other devices that get electricity from those circuits?

Christianswe26

I don't have anything plugged in to the 12v cigarette power socket. It appears that the major drain of battery is caused by fuse 19 in the fuse box in engine compartment. I can sometimes see a little spark when inserting the fuse into the fuse holder for fuse 19 so that would suggest a bigger battery drain.

What I've done now is that I put back fuse 19 and fuse 20 in the the fuse box but removed the little 10 A fuse inserted into the stereo (Audi concert 2 unit) and but the cables back on the stereo and locking the car. When doing so, there is a much smaller battery drain, about 0.2 A so my conclusion is that something inside the stereo is broken causing the battery drain of 1-1.2 Amps and also the hazzard light to illuminate.

When the fuse is removed from the stereo the hazzard light is off all the time, otherwise it would turn on every 60 seconds when there is a bigger battery drain. My dad is an electrician so he will open the stereo and check the circuit board to see if something is burnt or shorted out or something.

Yes the car's sound system is stock, I've got a big amplifier in the right side of the boot and to the left the BOSE subwoofer is located behind a cloth panel.

Christianswe26

Update:

The original stereo in the car didn't seem to have any electrical issues but just to be safe I purchased another used stereo with same article number and that didn't help as the hazard warning lamp is still turning on every 60 seconds when the car is locked.

I'm guessing it might be something with the telephone control module that is causing the battery drain as I get 2 different dtc's which are: 01301 and 01303.
My question is if any of you knows where the telephone control module is located in an Audi S3 8P? People say different things on the internet so it's difficult to know the exact location.