We use two steps: 1. Insert a medical-grade endoscope through the spark plug hole to visually inspect cylinder wall scratches and carbon buildup on the piston top; 2. Extract an engine oil sample to check for large metal debris or emulsification (caused by coolant leakage).

The lifespan of rubber sealing strips for frameless doors is usually only 4-5 years. We carefully press the sealing strip at the edge of the roof to check for loss of elasticity and use a high-pressure water gun to wash the seams of the windows to check for direct water leakage due to aging.

We will check if the vehicle identification number (VIN) is within the official recall batch. If there are any outstanding safety recalls (such as replacing Takata airbags), we will require the original owner to assist in sending it to an official 4S shop to complete the free recall work before the vehicle is deregistered.