Audi has issued a recall for approximately 9,000 examples of the 2013-2016 Audi A8 and the higher-performance S8. The affected vehicles carry different build dates and the recall is not VIN-sequential. The problem was eventually remedied on the assembly line.
The defect comes from the fuel system. According to the automaker, the high pressure fuel pump's supply line might become porous over time. This can cause a fuel smell to enter the cabin, and worse, it can create a fuel leak. A fuel leak in the presence of heat or a spark can become a fire hazard.
Audi first discovered the defect in June 2018. While it has tested and investigated from June 2018 to Jan. 2019, the automaker said in documents submitted to NHTSA that these tests "still did not provide a clear understanding of the root cause." However, during that time, it did discover a remedy that can, in Audi's words, "[ensure] the durability of the fuel supply line throughout the lifecycle of the vehicle."
For the remedy, Audi technicians will add a fuel pressure damper in the low pressure fuel supply, which is located in the gas tank. Those who have already paid Audi for the repair will be reimbursed. Vehicles produced after a certain point already contain the fuel damper, too. Owners should be notified via first-class mail starting in late March.