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Buying a used car , Know your car · 更新于 2026-10-15

How to read a VIN

The vehicle identification number (VIN) is a 17-character code that identifies one individual vehicle. Knowing roughly how it is built helps you spot mistakes and tampering. This guide explains the general structure used by most modern cars.

Where to find it

• On a plate or stamp visible through the windscreen at the base, on the driver's side.
• On a plate on the door pillar or inside the door frame.
• Stamped into the body or chassis, often in the engine bay or under a seat or the boot floor.
• On the registration document, service book and insurance papers.

The structure in three parts

A VIN has 17 characters made of capital letters and digits. The letters I, O and Q are never used, so they cannot be mistaken for 1 and 0.

1. Characters 1 to 3, the manufacturer code (WMI). They tell who built the vehicle and roughly where. The first character usually relates to the region or country of manufacture.
2. Characters 4 to 9, the descriptor section. The manufacturer uses these to describe features such as model, body type, engine and restraint systems. The coding differs between manufacturers. The ninth character is the check digit.
3. Characters 10 to 17, the identifier section. This is the part that makes the vehicle unique.

Check digit, model year and plant

The check digit is calculated from the other characters by a fixed formula. If a VIN is typed or altered incorrectly, the check digit often will not fit. Be aware that the formula is mandatory in some markets but not in others, so a mismatch in a car built for a different market is not always proof of a problem.

The tenth character is commonly used for the model year, using a repeating sequence of letters and digits. The eleventh character usually indicates the assembly plant. The remaining characters are the serial number of the vehicle.

What a VIN can and cannot tell you

Decoding a VIN can confirm basic facts such as manufacturer, approximate year and sometimes engine or body type. It does not by itself reveal accident history, mileage or the condition of the car. Use it as a starting point for further checks.

Warning signs of a mismatch

• The number on the car differs from the number on the papers, even by one character.
• Stamped characters look uneven, re-stamped, scratched or ground down.
• A plate that is loose, has damaged rivets or sits on fresh paint.
• Different numbers in different places on the same car.
• The model year or engine decoded from the VIN does not match what you see.

If anything looks wrong, do not continue with the purchase until the difference is fully explained and verified.

Documents Used car VIN