Exhaust flap
Opens or closes an exhaust path to change sound and back pressure.
In the rear silencer or a tailpipe section on equipped cars.
An electric or vacuum actuator swings a valve so gas can take a quieter or a freer route.
A volume knob built into the pipe.
Rattles, a stuck-loud or stuck-quiet exhaust or a fault message can involve the flap or its actuator.
Condition, contamination, operating pattern and the underlying engine matter more than a universal age limit.
Sensors and joints differ greatly from complete after-treatment assemblies. First repair the cause of contamination or abnormal combustion.
M Sport and M exhausts let the driver open the flaps through the driving-mode settings.
BMW combustion models; petrol and diesel after-treatment components differ by engine and market.