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).

It's extremely difficult. The security level of Chinese brand immobilizers is very high, and you must connect a specialized factory computer to the vehicle's OBD and be online with the domestic server to match it. Losing all keys usually means you need to replace the entire lock cylinder and anti-theft control module while overseas.

Experience turbo lag and power surge during road tests; check for significant oil accumulation at the turbo intake and intercooler connections (slight oil vapor is normal); and use OBD to read the real-time boost pressure peak to see if it meets factory settings.