yw12

I have a 2004 A8L and something weird is happening with the MMI. When i park the car in the sun and the dash warms up, the MMI pops and all systems work. When the
inside is cool or in the morning/evening , system wont turn on. system resets but doesnt start. some component is not reporting in and completing the loop. anyone have something similar? trying to narrow down which components is faulty. did replace the MMI unit (4E1919612H) IN NEW.
thanks

yw12

good news. problem is fix!!!!!
it was not easy but here is the brake down. there are three parts to the MMI. mmi screen,mmi control panel ,Bose amp. if any of the 3 don't work, the system wont work.
its fibre optic. in my car the screen was working well. the control panel was new. i had water come from the sun roof. the drain tubes where bloke.( very important to open them). a new control panel from AUDI is 500$. but still when it got cold the unit stop working. the screen goes on the 5 seconds and closes. so the problem must be the Bose amp at the back of the car. a new one is 1100$ but found on eBay used one for 240$.
after installation again it was not working well. i retread it and got one for 135$.
this one works 100% like new. bottom line, do research. my mechanic did all what i told him. otherwise it will take the mechanic days to find the fix. there are no error code when the Bose amp is not working well. i hope my story helps any A8 D3 with MMI problems.