Motore termico auto: codice motore, versioni e compatibilità. Immagine illustrativa CarlinFodera.

Car engine: engine code, versions, and compatibility

An internal combustion engine transforms fuel energy into motion through internal combustion. To choose a replacement engine, however, the most important distinction is not simply between petrol and diesel: you need to identify the exact version installed in the vehicle and compare it with the one offered, as well as verify what the supply includes.

Simplified illustrative diagram of the air, fuel and exhaust systems of an internal combustion engine

Petrol and diesel engines: general differences

In spark-ignition engines, combustion is initiated by a spark; in diesel engines, ignition occurs through compression. The actual architecture varies by generation and manufacturer: injection systems, forced induction, exhaust-gas after-treatment, sensors and control units are not interchangeable simply because the engine has a similar displacement or power output.

The distinction helps identify the technical family, but it is not enough to make a purchase. Even within the same model and fuel type, there may be different engine codes and revisions, with different auxiliary components, emissions systems, wiring or interfaces. Bosch documentation on powertrain systems describes families and components; the specific application must be confirmed through the vehicle manufacturer’s catalog.

Which data to identify

Illustrative details and neutral fields for checking the engine code and configuration

  • VIN and vehicle identification data, including production date and version;
  • the complete engine code and legible markings on the unit;
  • fuel type, power, displacement and emissions standard stated in the documentation;
  • control-unit and auxiliary-component codes, when the configuration makes them relevant;
  • any replacement codes or revisions indicated by the OEM catalog.

Regulation (EU) 2018/858 considers type, variant and version as identifiers of approved configurations and includes powertrain characteristics among the technical criteria. The registration document is not a parts catalog: use its data as a starting point and request an application check based on the VIN and codes.

The engine code is not the only check

An identical or similar code is an important clue, but it may not fully describe the supply, accessory level or updates introduced over time. Compare the donor engine with the receiving version using OEM sources and have the workshop check the interfaces with the gearbox, wiring, cooling, intake and exhaust systems. Do not infer suitability from the shape of the block or from a commercial designation alone.

To identify the references, consult the CarlinFodera guide to the OEM code and the guide to parts compatibility. For the distinction between the engine and its accessories, also read the complete engine guide and the overview of engine parts.

Used engine: condition and documentation

Request current photographs of the engine and its markings, documented information about the donor vehicle when available, declared damage, checks actually performed, and the components included or excluded. The statement “working” or “tested” is more useful if the seller explains the test and its limitations. A photograph does not certify internal wear; the absence of visible defects does not prove suitability for installation.

Compatibility, engine condition and the terms of sale are three independent checks. For the commercial aspect, consult the used parts guide. Before ordering and installing, ask the workshop to confirm the application and the operations required for that version according to the manufacturer’s documentation. Do not apply tightening torques, fluids or procedures taken from a different engine.

CarlinFodera examples to read carefully

The articles on the BMW families N47D20A, N20B20A/N20B20B and B47D20/B47C20A illustrate cases in which codes and configurations require a specific comparison. They concern the variants mentioned and are not lists of equivalent engines for other models.

Car internal combustion engine: engine code, versions and compatibility. Illustrative CarlinFodera image.

Authoritative sources

Sources consulted on October 3, 2026. General informational content; identification, compatibility and installation must be confirmed for the specific vehicle using OEM documentation and a professional. The images are illustrative diagrams and do not show an actual supply.

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