If you're using an automotive data provider for VIN decoding, you probably have a few vehicles in inventory that your data provider cannot decode. Some of these might be classic cars, vehicles sold in Europe or Asia then imported into the US, Trailers, or other types of vehicles that your data provider simply does not support. However, it's likely that some of these vehicles cannot be decoded because the VIN number is just plain incorrect, usually due to human error when reading the VIN off the vehicle. Fortunately, there are a number of ways to determine a VIN is invalid. You can employ these methods to isolate your invalid VINs and either make automated corrections or go back to the field to get the correct VIN off your vehicle.