2012 Audi S4 shut it down itself when I standby the car for the redlight. Where is the problem when that happened??

Thank you for responding. The ABS light and Air Pressure light was on, also the AC turn off and the radio turn off too. But everything back to normal when I restart the car right away, the ABS light and Air Pressure light are gone too. So any thought on this Would be greatly appreciated. Thank you

Ok, I see. Just like your computer at hokme or cell phone, the processors in cars lock up sometimes too. They can either cease to function until rebooted (restart thed car), or fail to perform some tasks due to a fault in software. Unless it happens again within a short period of time, I wouldn't be concerned at all.