RS3 battery issue?

[replicant71]

My 2026 RS3 is currently in with my local dealer investigating a potential battery issue.

A few weeks ago, shortly after I bought it, it came up with a warning message saying something like battery low, drive vehicle to charge it. Then over the next couple of weeks I noticed a couple of other electrical issues, like the keyless entry not working and the little red LED light on the drivers door (alarm/immobiliser), not flashing when locked.

Then last week, the car would not start at all, totally dead. Called out the AA, they managed to get it started with a jump start but it took quite a while. They scanned the battery and said it was only reading about 5v instead of what it should be, 12v. They told me to drive it for an hour to get it re-charged and then advised me to take it into Audi.

Local dealer is taking quite a while to look at it, they initially said the error log stated the "charging flap" was stuck. However, apparently, the RS3 does not have a charging flap ?! So they are continuing with their investigations.

The AA guy said it could be a faulty battery or something is draining it in the background.

Any one else had any issues like this?

 

[Daggerit]

My 2026 RS3 is currently in with my local dealer investigating a potential battery issue.

A few weeks ago, shortly after I bought it, it came up with a warning message saying something like battery low, drive vehicle to charge it. Then over the next couple of weeks I noticed a couple of other electrical issues, like the keyless entry not working and the little red LED light on the drivers door (alarm/immobiliser), not flashing when locked.

Then last week, the car would not start at all, totally dead. Called out the AA, they managed to get it started with a jump start but it took quite a while. They scanned the battery and said it was only reading about 5v instead of what it should be, 12v. They told me to drive it for an hour to get it re-charged and then advised me to take it into Audi.

Local dealer is taking quite a while to look at it, they initially said the error log stated the "charging flap" was stuck. However, apparently, the RS3 does not have a charging flap ?! So they are continuing with their investigations.

The AA guy said it could be a faulty battery or something is draining it in the background.

Any one else had any issues like this?

The only thing similar that I had was right when the car was delivered, literally off the back of the truck with 43 miles on the clock. Error message came up saying something about the charging not working properly, so phoned the AA who couldn’t diagnose through the error codes, so they started the car while I looked under the bonnet at which point I saw bits of the alternator belt flapping around because it was completely shredded and not turning any of the bits it was supposed to…

Doubt it’s that, but always good to look at the physical stuff rather than just what comes up on the scanner.


Sent from my iPhone using Tapatalk

 

[flybynite]

My 2026 RS3 is currently in with my local dealer investigating a potential battery issue.

A few weeks ago, shortly after I bought it, it came up with a warning message saying something like battery low, drive vehicle to charge it. Then over the next couple of weeks I noticed a couple of other electrical issues, like the keyless entry not working and the little red LED light on the drivers door (alarm/immobiliser), not flashing when locked.

Then last week, the car would not start at all, totally dead. Called out the AA, they managed to get it started with a jump start but it took quite a while. They scanned the battery and said it was only reading about 5v instead of what it should be, 12v. They told me to drive it for an hour to get it re-charged and then advised me to take it into Audi.

Local dealer is taking quite a while to look at it, they initially said the error log stated the "charging flap" was stuck. However, apparently, the RS3 does not have a charging flap ?! So they are continuing with their investigations.

The AA guy said it could be a faulty battery or something is draining it in the background.

Any one else had any issues like this?

Dealer software has two modes, expert (for master techs) only and idiot mode (for everyone else) Days gone by RS cars would be worked on by Master Techs but that has gone by the wind. I would ask the question who worked on it.

Often a good indi with VCDS can log and diagnose things better than a dealer with Odis. SFD2 makes it harder but most diagnostics still work. Sometimes they just need eyes as @Daggerit says above.

Not the first car to come new with a faulty battery, thy do not fit the best anyway. No new car battery has lasted more than 3 years for me. Not yet had to replace a single silver-top Varta I have replaced them with yet and that is knocking on 12 years for one of mine..

 

[replicant71]

So, picked up my RS3 today after it being with the dealer for four weeks. They could not find what was causing a possible drain of the battery so had to conclude that it was a faulty battery. However, the battery was already replaced when the car was only two months old, when the previous owner had it. What are the chances that TWO batteries are faulty?! Sounds unlikely to me.

So they have replaced the battery again, third time lucky and the car is only six months old!

However, I'm sceptical that they have even replaced it. I was expecting to have to re-do all my settings/user log etc, however, everything is as it was before. Surely if they disconnected the battery and replaced it with a new one, all my settings would be lost and it would effectively be like a factory reset???

Or does the car somehow retain settings etc even when the battery is replaced?

 

[JKP]

I've heard that in many, if not most, cars nowadays a temporary power source must be connected during the battery replacement. If they have done that, I see no reason why the car would have reset.

Another thought, if your battery was already totally drained and not a single sign of power anywhere but still the car didn't reset, looks like the hard drive of the car can keep the settings stored even without any power.

 

[GBJBAZDO]

I purchased my brand new (76 plate) RS3 just 3 weeks ago and last week, I went to open the car and it wouldn't unlock and the alarm started to sound - both my new key fobs wouldn't work (convenience key turned off from new). Realising I couldn't get into the car I removed the door handle plastic bit to reveal the lock and opened the drivers door with the key. I then couldn't turn on the ignition and only the electric seats worked. In the other words the car was pretty much dead. At this point I began to read the manual to locate the fuse boxes (one in engine compartment and one in glove box behind panel) whilst at the time time phoning Audi assist. While I could have started removing the fuses I decided not to and wait for the technician. On his arrival he said we needed a battery reset so I had to climb over the front seat and into the boot to manually release the boot so we could gain access to the battery. Once in the boot we disconnected the battery for 30 seconds and on re connection the car came alive and I was able to start it. He then plugged in the diagnostic tool and had to reset a number of fault codes whilst having to turn the steering wheel full lock right then full lock left to reset the steering electronics. I rebooted the MMI and all was back to normal. The Technician found no errors on the diagnostics relating to why this could of occurred and said it was possibly a software fault. Whilst this is not the same issue as above I thought I'd share my experience for interest. It's scary how modern cars now have too many electrical components controlled by software and that a glitch can render your car completely inoperable. Hopefully a one off but we will see!

 

[Mike.46]

If the OP's car has already had one battery replaced and now a second one the car is either not charging correctly or there is a parasitic drain on the battery itself, I have looked at quite a few similar problem cars over the years, the difficult part is connecting your DVM (digital volt meter set to 'amps') across where you are about to disconnect the battery so the car does not see a break in supply voltage and leaving doors and bonnets open but tricking the car into thinking they are closed so it can go into 'sleep mode'

Usual suspects from years ago were boot lights not switching off, alarm systems and sound amplifiers etc,

Todays cars are massively over complicated (IMHO) running loads of systems after you lock them and controlling stuff that doesnt need controlling (Like the alternator that works harder when you are slowing down and another that switches stuff 'off' as the battery voltage decreases), it's just a waiting game watching the meter to see what the resting draw in milliamps ends up at and then trying to work out what hasnt switched off and why it hasnt

 

[replicant71]

Just to update this, after a couple of months of my car being with the dealer, they eventually tracked down what was draining the battery. It was the lane assist radars that are located within the rear bumper. Basically, when the car was turned off and locked, the radars were staying "on" and then draining the battery.

They replaced both radars under warranty, and, touch wood, it's been ok since.

As mentioned, modern cars have so much tech and electronics that it only takes something minor or a sensor to play up and the car goes into meltdown!

 

[JKP]

Sounds like an issue almost impossible to chase down. Good to hear they finally found the reason but that's insane time for the dealer to keep your car in.

 

[Mike.46]

Sounds like an issue almost impossible to chase down. Good to hear they finally found the reason but that's insane time for the dealer to keep your car in.

It's hugely time consuming, watching a meter probably measuring around 3-400 milliamps maybe more and then either pulling fuses or similar until the reading reduces to somewhere around 10-20 milliamps and usually 'waking' the car up along the way and having to wait a while for it to go back to sleep
Took ages on my lads Q7, eventually it was found to be the Bose amplifier