Audi A3, trunk warning light flashing

You didn't mention the obvious, fuses. In many euro cars there are multiple fuses for each light circuit, side to side, and inside to outside, so check fuses, even if it looks good, they can still be bad. Switch with same amp and color fuse with any other same specs to narrow it down. Fuses can be tricky believe it or not, and I can't tell you how many times people overlook the obvious, even mechanics.
Good luck,
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The light will go out if you have ALL bulbs working correctly and have the CORRECT bulbs installed. Check again.

Bonnet not closed properly

fuse problem

Could be a fuse or a relay prob. Hopefully it's not an indicator stalk switch problem (expensive). If your hazard warning lights switch works then it's not the fuse or the relay. If your A3 is still under warranty then get your Audi dealer to fix it. If not it won't pass the 'MOT'. Get it sorted before someone rear-ends you while you're turning!

Take it to auto zone and have the code's reader hooked up on it and that can tell you the problem

the indicator lights flashing constantly might be a warning from the car that all the doors have not been closed properly

after writing this ^^ i think that the system that tells the car if the door is open or closed it damaged or broken
and needs replacing

try leaving all the doors open and lock the car do the indicator lights flash contantly?

you need to get a dianostics done but due to the reson that it is intermmitant the problem will not exist when you get to the garage

check all the sensors that tell the car if the door is open firstly

if it says the trunk is open when it really is closed you will need to replace the trunk latch

hallo
i belive it is oxygen sensor (O2S)
Marko

boot? an indicator light is on means something is not shut such as a door please clarify boot