Since automobile manufacturers use different engine coding schemes for their products, it is necessary to consult a manufacturer-specific reference to understand the coding scheme for a particular engine block. Automotive enthusiast websites such as MustangTek.com often provide guides to the format of codes for a particular manufacturer as well as the engine codes associated with specific model years and option levels of vehicles.
Although all manufacturers use different engine coding schemes, the Ford engine block code provides an easily understood example of the types of information incorporated in engine block codes. Ford engine codes used during the 20th century consist of a four-character code in which the first two characters identify the decade and year of manufacture. The second two characters indicate the vehicle model and internal Ford parts source for the part. These are then followed by an alphanumeric part number that may also include information about which specific vehicle variants that the part is associated with. Ford used this system for identifying all parts of the vehicle in addition to identifying the engine block itself.
One of the most common uses for engine codes is to determine if a vehicle contains its original factory parts at resale. Since vehicles with original engines are often worth more than those with replacement parts, unscrupulous sellers may claim that a car has its original engine even if some or all of its components have been replaced. Confirming that the engine code conforms to one used in the production run helps buyers avoid fraud.