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.

We will never perform blind deep disassembly unless there are clear severe fault codes or extreme noises. The sealing of the engine and transmission is crucial, and compromising the factory seals to investigate non-existent issues is unprofessional. We rely on data flow and external acoustic and fluid analysis to make judgments.

During the stationary steering test, the technician will check the smoothness of the steering wheel from full left to full right, looking for any unusual noises from the steering gear; they will also inspect the hydraulic power steering pump (if present) and the seals of the steering column for any hydraulic fluid leakage.