We maintain an absolute skeptical attitude. In addition to regular visual inspections, we focus on checking for sediment accumulation around the sunroof drainage channels and look for water stains under the A-pillar trim and front floor mats. This is the only effective physical evidence to determine if the sunroof drainage holes are blocked, leading to hidden leaks.

This involves personal privacy, and we have no right or ability to retrieve personal driving violation records from the traffic police system. We can only infer if there was aggressive driving by checking if the engine has been reprogrammed with a higher-level ECU (stage 1/2) or if the transmission has a history of severe overheating.

An OBD scan is one of the most cost-effective tools in a remote pre-purchase inspection, but you need to know what it can and cannot tell you. What it reveals well: current and stored fault codes across the engine, transmission, ABS, airbag, and body modules. A car with dozens of cleared codes in multiple modules may have electrical problems or a history of tampering. It also shows readiness monitors — if all monitors show 「not ready」 on a car that claims to be freshly serviced, the codes were probably cleared recently to hide something. What it reveals with the right software: live data. You can watch engine idle stability, coolant temperature under load, transmission shift behavior, and battery cell voltages on EVs. Abnormal fuel trims or misfire counters can flag worn injectors or coils before any warning light appears. What it cannot do: prove real mileage (odometers can be corrected digitally), detect physical accident repairs, or judge paint and rust. Practical advice: ask your inspector for a full-system scan report with screenshots, not just a 「no codes」 verbal summary. For Chinese brands, make sure the tool supports their protocols — mainstream scanners cover BYD, Geely, and Chery well, but some small brands need brand-specific software.