Why does my Toyota Camry Hybrid make a high-pitched noise when parked?

A high-pitched whine, hum, or buzzing sound from a Toyota Camry Hybrid while parked is often normal. Hybrids can keep certain pumps, fans, and self-check systems running briefly after shutdown.

Common causes include:

• Brake accumulator pump: You may hear a whine or mechanical pumping sound right after shutdown or when opening the driver’s door. This is usually the brake system pressurizing or depressurizing.
• Inverter coolant pump: A humming sound near the front of the car can come from the pump that keeps the hybrid inverter cool for a short time after the vehicle is turned off.
• Battery cooling fan: A whirring sound from the rear seat or cargo area can be the battery cooling fan running after a drive.
• Emissions or system self-checks: Some Toyota vehicles can run diagnostic checks after parking, which may create brief buzzing or humming sounds.

If the noise is extremely loud, happens constantly, or comes with warning lights, have the vehicle inspected by a Toyota dealer or qualified mechanic. Exact timing and sound sources can vary by model year and trim, so checking the owner’s manual or Toyota service information is a good idea.