Working on a 2008 Audi A6. We diagnosed an issue with the check engine light coming on but not causing any driveability issues and we inspected for needed maintenance. We also checked the a/c system due to the a/c not cooling well. We topped off the refrigerant in the a/c system but found no signs of leaks, we replaced a defective windshield washer pump, replaced the engine belt, tensioner and idler pulley and we did a top end clean to reduce carbon build up in the intake manifold that was causing the intake manifold adjuster to stick at times.