With multiple recalls over the years, the coil packs in Audi vehicles are known to have serious issues due to manufacturer defects. In many cases, Audi will replace faulty coil packs at no charge.
Symptoms of faulty coil packs include rough idle and a blinking check engine light (CEL). In severe cases, the engine runs extremely rough, making the vehicle not drivable. The only way to check for defective coil packs is by removing the engine cover, looking at the pack's model number and then asking an Audi dealer.
Most of the coil packs that go bad in Audi vehicles are defective -- they were either manufactured or installed improperly. A defective coil pack will usually operate normally for more than 10,000 miles before going bad. Cold weather can also cause a defective coil pack to malfunction.
Driving with a malfunctioning coil pack can cause damage to the catalytic converter, increased wear on the cylinder wall and early wear on the bearings. These things are caused by unspent fuel being leaked into various engine and exhaust parts.