Diagnosis
The most common cause of a sticky throttle on the Mi Scooter 4 Pro is a buildup of dirt, dust, or road grime that has seeped into the small gap around the throttle paddle's pivot point, creating a gummy residue. Less frequently, the small internal metal return spring can become fatigued, corroded, or dislodged, losing its ability to pull the throttle back to the neutral position.
How to Fix It
Start with a thorough cleaning. Power the scooter completely off. Use a can of compressed air to blast away loose debris from around the throttle's base. Then, apply a small amount of isopropyl alcohol (90% or higher) with a cotton swab or soft brush directly into the seam where the paddle meets the housing. While the alcohol is wet, vigorously work the throttle lever back and forth dozens of times to dissolve and dislodge the grime. Use more alcohol and clean swabs until no more dirt is being removed. Allow it to air dry completely for 5-10 minutes before testing.
If That Didn't Work
If cleaning doesn't restore a crisp, reliable return, the entire throttle assembly must be replaced. For the 4 Pro, this is a single, sealed unit. You'll need to carefully remove the handlebar grip and open the central console housing to access the throttle's wiring connector and mounting screws. Swap the old unit for a new OEM Xiaomi throttle module, ensuring the wiring connector is firmly seated before reassembling the console.
Heads Up
Never ride with a malfunctioning throttle. A sticky or slow-returning throttle can lead to unintended acceleration, which is extremely dangerous. Always perform a static test—pushing the throttle and releasing it—to confirm it snaps back instantly and audibly before every ride.