Android Auto fails for nine common reasons, and Google's own fix list starts with the one nobody suspects: the cable. Fix eight costs nothing but a menu tap.
Google is blunt about this: Android Auto won't work on all cars equipped with a USB port. Look your model up on android.com/auto before you blame the phone.
If Android Auto worked before and stopped, Google says replacing the USB cable will likely fix it. Cables die quietly from being bent in the same spot daily.
Google's guidance is specific: use a cable under 3 feet, or 1 metre, and avoid extensions. Plug straight into the car's own USB socket, never a hub or adapter.
Google suggests reaching for the original cable packaged with your phone. Third-party cables work too, but only if they meet USB Implementers Forum standards.
Android Auto has its own switch inside the car's infotainment settings, separate from anything on your phone. Confirm it is turned on there before going further.
Google lists restarting the car's infotainment system as a standard fix. Check your car's manual for the method, because it differs between manufacturers.
Trouble with a second car? On the phone: Settings, Connected devices, Connection preferences, Android Auto, Previously connected cars, then Forget all cars.
Wired needs Android 9.0 Pie and a data plan. Wireless needs Android 11 or newer plus a phone supporting 5 GHz Wi-Fi, so an older handset simply cannot do it.
Running a Pioneer, Kenwood or other aftermarket receiver? Google points you to the manufacturer's own website to check whether a firmware update is available.
A connection that fails is one problem. One that dies mid-drive is another, and Google has shipped Android Auto updates aimed squarely at that second kind.