Exhaust Flap
Definition
Exhaust flaps are electronically controlled valves in AMG and sport exhausts that open for a louder, freer-flowing sound and close for a quieter one.
An exhaust flap, also called an exhaust valve, is a movable plate inside the exhaust system. When it is closed, exhaust gas takes a longer path through the mufflers and the car sounds quieter. When it opens, the gas takes a shorter, freer path and the sound gets louder and deeper.
Where you find them
Flaps are standard on many Mercedes-AMG models and part of the AMG Performance exhaust or sport exhaust on others. An actuator moves each flap, and a control unit decides when to open or close it.
What decides when they open
- Drive program - in DYNAMIC SELECT Comfort the flaps stay closed most of the time, in Sport and Sport+ they open more often.
- The exhaust button - cars with a performance exhaust often have a button that switches between a loud and a quiet setting.
- Engine speed and load - the software also opens or closes the flaps depending on revs, load and speed.
As a result, the factory logic often decides for the driver: the car may be quiet when you want sound, or loud on a cold start in your driveway.
Choosing the position yourself
An exhaust flap selection module lets you open and close the flaps in any drive program, including Comfort and Individual, so you choose the sound independently of the other settings. It works with the existing flaps and controls. Availability depends on the chassis code and exhaust system, and the volume should stay within the noise rules where you drive.