Improper VANOS function will cause reduced power and poor fuel economy. The VANOS system is BMWs version of variable valve timing and can be found on the intake and or exhaust camshafts. The system uses a pair of electrically actuated solenoids that direct the flow of pressurized oil to the VANOS gears. Depending on engine requirements the VANOS system can advance or retard timing as requested by the ECU.
