Q: What does 'auxiliary battery malfunction' mean? Also, I hit a trailer and broke a taillight yesterday, should I go to repair shop or dealer?

Your car has two batteries. One conventional sized battery manages the heavy loads like the starter and one smaller battery manages the body loads. The smaller battery is the auxiliary battery and it must be failing. Part of the point in the dual battery system is to keep you safely operating when one fails, so you may not notice anything besides the warning, but you should get the battery replaced to prevent any other problems. As for the taillights, if you don’t have any warnings on your dashboard and the lights are functioning, you could get away with replacing the lense yourself, but if the operation of the taillight has been affected, the car needs to be serviced by someone with the factory diagnostic equipment. The lighting systems are very complicated on these cars -like everything else- and the system will need to be scanned if any of the lights are broken. Contact Your Mechanic if you want to have a technician come out to your home or office and fix your taillight and your battery right there on the spot.