Water sitting in battery tray!!


Registered User
Apr 15, 2012
Reaction score
There's loads of water in there!!!ive read that the drainage holes clog up...were are they and how do I clean them out folks??
undo the battery and remove it, directly underneith the battery is a rubber bung, just push it in or pull it out of it place problem sold. i do this on every service now its such a common problem
Get the water out ASAP...mine filled up during a huge rain storm and got into the car. Water collected under the passenger footwell and fried the CCM....costly. I tried to remove the battery but couldnt get it past the wipers so in the end simply pushed the rubber bung completely inwards and left it that way...water drained and problem solved, well, that problem at least! That was the last straw with my a4 and I drive an 11 year old merc now...
I have just had this exact same issue with mine after we had some horrendous rain last week. The battery is a bit of a nightmare to get out and weighs a tonne!! I didnt realise that there was a bung underneath the battery cover, i just cleaned out the bung under the brake servo and that allowed the water to drain out. I actually just pushed the bung through, will this cause any issues ? Will the bung just be sitting in the drain somewhere now ?
the bung will be on the road by now, i pushed mine out of my passat when it was new, they are a stupid design
the bung will be on the road by now, i pushed mine out of my passat when it was new, they are a stupid design

I have been reading a few posts on various forums saying that by removing the bungs, you can cause some funny/horrible smells to come in to the cab through the heaters. I didnt touch the bung underneath my battery, i havent had a look at that one yet. Should i remove that one fully or just clean it out ?
Just push it through where it sits and leave it. No funny smells will accur.
It's like Audi purposely put the battery in a crap place. Didn't realise first off what a stupid place the screwn is holding the clamp in place nd then removing the battery is back killer!
Yeah, nightmare thing to get out! I posted about this water in the bulkhead issue on the 2.0TDI injector thread in April… reason being I had my car booked into audi for the injector/loom service campaign but had the water come into the car so had to cancel the injector appointment to put the car into an indie for repairs first. Car had to be repaired before being repaired, Lol! I intended to post this on a new thread however being away with work for ages I never got around to doing this….so will do now to put it in the propper place.
The non-ranting version is:
After a huge rain storm I noticed dampness in the passenger foot well carpet. The car had been in a smash days before so I assumed there was structural damage (it got a heck of a skelp from the port side..) and water was getting in somehow….. Next time out I could hear water sloshing around when cornering and stupidly thought I would take a look later on…. On way home from work lost comfort electrics: central locking; electric windows; interior lighting; boot and petrol cap release and alarm sounding whilst driving.
On investigation the bulkhead was almost full up with water. I popped the rubber bung to the left of the battery and the water drained out. Got home and pulled up the front passenger foot well carpet to find the place swimming…guess it must have been happening for awhile. I siphoned out several litres of water and used scrunched up old newspapers to remove more…..no joy getting electrics back. Put the car into a local guy I trust but ccm beyond help. New ccm and loads more drying out and got car back working fine.
Yes, I would strongly agree with pushing the bung through and leaving it out for anyone with these cars. Would hate someone else to have the costly replacement of the module and the dampness in the carpet and foam to get rid off which is a real pain.
Hi All,

New member here. I have a 2006 B7 and I recently experienced this problem. Seems like it was due to lots of organic material (leaves) clogging the drain hole. I first cleaned that out and then took this video showing the water draining properly. It was driving me nuts to not be able to "visualize" this area underneath the battery so I thought others may enjoy seeing this video that I took:

Audi A4 B7 water leaking into cabin pt 2 - YouTube (I did eventually get the bigger "bung" out - by pushing it through the bottom)
2001 S4 - Water drain under battery. Trough can fill with over a gallon of water. Clean 2 times a year if you live near trees. Easy fix. Worst part is trying to dry out carpets.
Yep - just had that one. Been having intermittent starting issues with all drive lights on (not flashing. ) Turns out some muppet had cut the side off the ecu cover off so dirt and leaves and water had got in to the ecu box (new cover on). Then I spotted 3" of water by the battery so had to tug that out and push out the drain hole which isnt even the lowest point?? Hope it drys out and gets rid of my start issue. Theres some plastic scuttle panels missing so thats why water runs down the screen and straight into the battery area and elsewhere - need to go off and find those now!

Similar threads