One problem related to manifold/header/muffler/tail pipe has been reported for the 2009 Audi A4. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2009 Audi A4 based on all problems reported for the 2009 A4.
Two faulty mis fires caused car to misfire and run rough and jolt. Car was towed to the closest Audi dealership for repairs. Subsequently, within the next 9 months, the care again exhibited close to the same symptoms and the car was again towed to the closest Audi dealership. This time, the intake manifold was cracked and was replaced. With a service bulletin out on this vehicle on these exact issues, I was still charged a $250 deductible per incident ($500 total) on my extended warranty to replace both the injectors and the intake manifold. According to the service bulletin, I should not have been charged.