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).

To prevent intermittent failures due to aging of the resistance wire, we will start the engine and set the seat heating/ventilation to maximum for at least 5 minutes, confirming significant temperature changes or airflow output in the cushion and backrest using an infrared thermometer or body sensor.

There are various reasons, including but not limited to: financial needs, restrictions from lottery policies, moving abroad, or dissatisfaction with certain features of the vehicle. We will ensure that the vehicle was not sold due to catastrophic failures by ruling out major accidents, water damage, and flooding.