Hi, I new to the forum and I am looking for any ideas on this one please.

My car won't start (was perfect up to locking it when at work) dashboard does not turn on, central locking won't work, all of the electrics seem to have shut down.

I had the car recovered to a local garage but I'm not sure they will have the experience to get it going.

Had to access the boot opener from inside the car just to open the boot to see the battery.

Breakdown guy tested the battery and it was good with 12v, there are circuit breakers on the leads so does anyone have any experience of this happening?

Last resort will be getting it to an audi dealer, it's only an 2018 plate and 24k miles done, excellent condition and always serviced.

Any thoughts please?

 

2 hours ago, Kev Pratt said:

Hi, I new to the forum and I am looking for any ideas on this one please.

My car won't start (was perfect up to locking it when at work) dashboard does not turn on, central locking won't work, all of the electrics seem to have shut down.

I had the car recovered to a local garage but I'm not sure they will have the experience to get it going.

Had to access the boot opener from inside the car just to open the boot to see the battery.

Breakdown guy tested the battery and it was good with 12v, there are circuit breakers on the leads so does anyone have any experience of this happening?

Last resort will be getting it to an audi dealer, it's only an 2018 plate and 24k miles done, excellent condition and always serviced.

Any thoughts please?

 

Hi I am pretty sure it will be the battery if its never been changed as they suffer when old with voltage drops, the system is designed to shut itself down when it feels its being tampered with and a large voltage drop in cold weather will cause that, twelve volts as it is now proves not a lot, twelve volts running with everything turned on will prove an ailing battery or alternator as it should be twelve point five or over.

Steve.

Hi Steve, when the breakdown mechanic looked at it, he tried to jump start it from the engine and the battery itself, but nothing so should that have got the dashboard lit up?

I've read on the forums that there is an in-line fuse on the battery cable, hopefully it's something simple 😀. 

Thanks for the reply 

Regards Kev

First thing to do is get a multimeter on the battery. Should be in region of 12.4v-12.7v (not running). If you have to replace battery, usually AGM version and yes needs coded to the car with VCDS or similar. Check vent pipe when hooking up. I would normally trickle charge before installing.

You can replace battery and not code to get you up and running, but get it coded ASAP.

My understanding on the in-line fuse is it trips if airbags deploy, etc. Details here. 

 

Edited December 26, 2025Dec 26 by spartacus 68

Thanks Spartacus, I'm sure the garage its at now will go through the process of elimination (they don't open until the 7th Jan though!!) unfortunately as it's there and I don't have the tools for this it's all out of my hands now.   Let's hope the battery and coding it will get it running.

Thanks for your comments

 

I recently had some of the same symptoms with my 2015 Audi A4 Quattro. I had to crawl through to open the boot as well. Once I had it open I pulled out my spare tire to check the battery underneath. It ended up being the 110-amp HSB strip fuse that needed to be replaced. Located on the positive terminal of the battery. This is a high-current, bolt-down fuse that protects major electrical systems (main power distribution/charging circuits). It’s not a regular blade fuse. 

I was told it typically protects power distribution circuits such as the alternator charging system, engine-bay fuse panel, and other high-draw modules (ABS/ESC, electric steering, cooling fans, etc., depending on trim/VIN). If there’s a short or overload, this fuse blows to prevent wiring damage or electrical fires.

 

It’s usually located near the battery or engine-bay fuse block, not inside the cabin. When it fails, symptoms can include no-start, loss of charging, multiple warning lights, or sudden electrical shutdown.

 

OEM Littelfuse matters here—correct amperage and design are critical. Always disconnect the battery before replacing and never substitute a higher-amp fuse.

Once I replaced that fuse, the issues were resolved. Definitely worth checking if you’re seeing multiple electrical problems or power loss at the same time. I plan to get diagnostics done next week, the fuse did its job but I want to know what caused it. 

Thanks for the detailed response, hopefully it will be a fix the local garage can do without a visit to the dreaded audi dealer and I will be coughing up lots of £££.  Like you say there are so many electrical safeguards in cars these day's which seem to over complicate fixes 😀 

Regards Kev 

Just an update on my problem, the car ended up at the local main dealer, who said I had to commit to a 3 hour assessment period at £162/ph 😐.

They eventually identified the issue as a Convenience ECU J393 defective.

This is located in the boot by the passenger side rear lights.

So a total cost of £1360, oh and £300 to have it transported to the garage.

Audi not the best for a car with 26k miles on the clock 😒 

 

 

13 hours ago, Kev Pratt said:

Just an update on my problem, the car ended up at the local main dealer, who said I had to commit to a 3 hour assessment period at £162/ph 😐.

They eventually identified the issue as a Convenience ECU J393 defective.

This is located in the boot by the passenger side rear lights.

So a total cost of £1360, oh and £300 to have it transported to the garage.

Audi not the best for a car with 26k miles on the clock 😒 

 

 

Sorry to hear of this outcome. Was there any good will from Audi due to the mileage covered? 

No not at all, just  a repair to them im afraid 

4 hours ago, Kev Pratt said:

No not at all, just  a repair to them im afraid 

That's annoying, you'd have thought there would have been some good will. 

I doubt there would be any goodwill from Audi on a seven year old car, no matter how small the mileage.

1 hour ago, cliffcoggin said:

I doubt there would be any goodwill from Audi on a seven year old car, no matter how small the mileage.

Do Audi ever show any goodwill to any customer, rather like waiting for the second coming.

Steve.

2 minutes ago, Stevey Y said:

 like waiting for the second coming.

Or manure from a rocking horse.