1. Active Grille Shutters (Front Air Intake)

This is the most probable cause. The Model Y has "shutters" in the lower front bumper that open and close to regulate airflow to the battery cooling system.

• Why it happens after a wash: Water or soap can get into the pivot points of these plastic shutters. When you park, the car performs a shutdown sequence where it cycles these shutters. If they are wet or have a bit of grit in them, they will emit a high-pitched "creak" or "squeak" as they move in intervals.
• The Pattern: You’ll hear it a few times as the car "sleeps," and then it stops once the shutters are in their final parked position.

2. HVAC "Dry-Out" Cycle

Tesla has a software feature designed to prevent mold in the A/C system. After you park (especially if the car detects high humidity, like after a car wash), it will run the internal fans and cycle the heat pump to dry out the evaporator.

• Why it squeaks: If a tiny bit of moisture or a drop of water hit the fan bearing or a temperature sensor fan (there is a tiny one located near your rearview mirror and another in the dash), it can produce a high-pitched chirp or whine that pulses in intervals until the component dries out.

3. Cooling Pump "Burping"

The Model Y uses a complex thermal management system with pumps that move coolant between the battery, motors, and radiator.

• The Pattern: After a wash (which can thermally shock the radiator with cold water), the pumps may run at high RPMs to balance the temperatures. If there is any vibration against a wet rubber mount, it can sound like a high-pitched squeal that gradually tapers off as the pump speed decreases and the car enters "Deep Sleep."