By understanding that "ageing" means "slow reaction time," you can avoid throwing parts at the car and confidently replace the sensor, restoring your BMW's fuel efficiency and turning off that stubborn Check Engine Light for good.
The lower active air flap utilizes an electric stepper motor housed inside a plastic casing. Over years of continuous cycling, the small plastic reduction gears inside the motor strip, causing the motor to spin freely without actually moving the physical blind link.