We will use a megohmmeter (insulation resistance tester) to measure the insulation resistance of the high-voltage bus. If the resistance value is below the national safety standard, it indicates a risk of leakage, and the vehicle will be deemed unqualified.

Ask the exporter for a copy of the vehicle registration certificate (机动车登记证书). It lists every owner change and any mortgage registration. If the car was financed, there will be a lien entry; make sure a release entry follows it. You can also verify the VIN against public records through the traffic management platform (12123) — a legitimate exporter can generate a status report on the spot. Check that the seller's company name on the invoice matches the registered owner. For extra safety, require a written statement that the vehicle is free of liens, loans, court seizures, and lease agreements, and wire payment only to the company's corporate account after ownership is transferred to the export entity. That sequence — transfer first, payment second — is your strongest protection.

Once the car system (especially in a closed ecosystem) undergoes a major version upgrade, its bootloader is usually locked, preventing downgrades. If this happens, there is basically no solution in an overseas environment. Therefore, we strongly warn: do not blindly insert a USB drive to upgrade while offline.