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).

This is a typical case of "secondary damage caused by unprofessional rescue." Many hybrid vehicles require access to "maintenance mode" via engineering computers to allow the water pump to run at full speed for exhaust. We do not bear any moral or financial responsibility for cylinder damage caused by local technicians' misoperation.

We will honestly inform you of the common issues with this model (such as the water pump failure in certain German cars) and show that this car has had the improved parts replaced.