How to read a VIN: the 17 characters, position by position

One pattern for every vehicle sold in the United States

Every vehicle built for the US market carries a vehicle identification number of exactly 17 characters. Federal rule 49 CFR § 565.13 says so in one line: each VIN shall consist of seventeen characters, and the same rule requires that no two vehicles subject to the federal safety standards built within a 60-year period starting with the 1980 model year share a VIN. The manufacturer assigns the number, and it has to appear clearly and indelibly on the vehicle itself.

The characters are digits and capital letters, with three letters left out on purpose: I, O and Q are never used, because they are too easy to confuse with 1 and 0. Everything else in this guide follows § 565.15, the section that says what each group of positions must contain.

Positions 1 to 3: who built it

The first three characters are the manufacturer identifier, usually called the world manufacturer identifier or WMI. For a high-volume manufacturer, one that builds 1,000 or more vehicles of a type each year, these three characters alone identify the maker and the type of vehicle, such as passenger car, truck or multipurpose vehicle. The identifiers are assigned through SAE International under an arrangement with NHTSA, which is why the same company can own many of them: one for each plant and vehicle type.

A 9 in the third position is a signal. It means the manufacturer is a low-volume builder whose identifier is six characters long: positions 1 to 3 together with positions 12 to 14. Small builders of specialty vehicles and trailers use this scheme.

• The first character usually points to the country or region of manufacture, but the rule defines the three characters only as a unique manufacturer code.
• Two vehicles from the same company can start differently: a car and a truck from the same plant get different third characters.
• The PlateVIN make pages list the identifiers NHTSA associates with each make, with country and vehicle type.

Positions 4 to 8: what kind of vehicle

The next five characters describe the vehicle. The manufacturer chooses which characters to use and where, so there is no universal table to look up. What the rule fixes is the information that must be recoverable from them. For a passenger car it is make, line, series, body type, engine type and all restraint devices and their location. For a truck it adds the chassis, cab type, brake system and gross vehicle weight rating.

Manufacturers must give NHTSA the key to their codes (§ 565.16), and that key is what a decoder such as NHTSA vPIC applies. One detail you can check by eye: for passenger cars, and for multipurpose vehicles and trucks of 10,000 pounds or less, the character in position 7 must be a letter. It matters for reading the model year, as the guide on model-year codes explains.

Position 9: the check digit

Position 9 is a single digit or the letter X, calculated from every other character. It exists only to catch transcription mistakes: a VIN with a wrong ninth character was probably mistyped or misread. The separate guide on the check digit walks through the calculation with the example federal regulation gives.

Positions 10 to 17: which one

Position 10 is the model-year code, position 11 is the code of the plant where the vehicle was assembled, and positions 12 to 17 are the number the manufacturer assigned in sequence in production. For passenger cars and light trucks the last five characters must be digits; for heavier vehicles the last four.

Together these eight characters are what make a VIN unique. Two cars of the same model, year and plant differ only in the serial number, which is why a single wrong digit points to a different car.

What you can and cannot read by eye

By eye you can read the manufacturer code if you know the list, the model-year letter if you know Table VII, and the plant code only with the manufacturer’s key. The vehicle attributes and the engine are not readable without the decoder key. That is the work PlateVIN hands to NHTSA vPIC: it applies the manufacturers’ keys and returns make, model, trim, engine, body class, restraints and plant in plain words.

Källor

• 49 CFR § 565.13 General requirements (eCFR)
• 49 CFR § 565.15 Content requirements (eCFR)
• 49 CFR § 565.16 Reporting requirements (eCFR)
• NHTSA vPIC API documentation