Fuel quality must be maintained to avoid engine misfire problems; the misfires may cause the Check Engine Light to illuminate.
Car Problem Reports
Audi A6 Maintain Fuel Quality to Avoid Misfires and CEL Illumination
Audi A6 Problem
Engines Affected: 2.8L V6, 3.0L V6
Average Mileage: 91,000 mi (80,000 mi - 102,000 mi)
Visitor, 1999 Audi A6, 2.8L V6, 102,000 mi
My daughter started to use it and put 87 gasoline froom ^^. Some days after the engine light came on andd you could sense there was a cylinder miss firing. changed to ptremium shell and problem was gone