How to check engine number
The engine number is an identification number marked on the engine of a vehicle. Unlike the 17-character VIN, which identifies the whole car, the engine number identifies the specific engine fitted at the factory. The format varies by manufacturer, but it usually combines an engine code (identifying the engine type) with a serial number unique to that unit.
Where to find it
The engine number is stamped or etched directly onto the engine block, though the exact location differs between makes – it is often on a flat machined surface near the front or side of the block, and can be hidden under covers or hoses. Your owner’s handbook will normally tell you where to look. The number is also recorded on the car’s V5C registration certificate (logbook), and some cars repeat it on the VIN plate or a sticker in the engine bay.
Why it matters when buying a used car
When viewing a used car, compare the engine number stamped on the engine with the one printed on the V5C. If they do not match, the engine has been replaced at some point. That is not automatically a problem – engines are legitimately swapped after failures – but the change should have been reported to the DVLA and reflected in the logbook. An unexplained mismatch can point to an undocumented replacement, a stolen engine, or a cloned vehicle, so ask the seller for evidence such as receipts before going any further.
Checking the engine number, VIN and registration together is one of the simplest ways to spot a suspect car. Pair the physical inspection with a full car history check to confirm what the DVLA holds on record.