The vehicles recalled are the 2013-2017 A5 and Q5, the 2013-2016 A4 sedan and Allroad, and those 2012-2015 A6 fitted with the four cylinder Turbo FSI engine. The electric coolant pump fitted in these engines could overheat or short-circuit, and as such it might cause a fire. No injuries or crashes related to the issue have been reported. The manufacturer hasn't yet announced when parts will become available for the repair, but dealers will replace the pumps free of charge when possible.
This is actually the second time these exact vehicles are being recalled for a coolant pump issue: earlier in January 2017, the matter was attempted to be tackled via software, as the pump's power supply would be automatically cut if debris blocked it. But that doesn't seem to have circumvented the issue properly, and as a result Audi is replacing the entire pumps a little more than a year later.