How Do I Know if I Have an M54 or M56 BMW 6-Cylinder Engine?
The non-M BMW 6-cylinder engines used in the US market BMW 3, 5, X and Z models from the Early 2000s through mid 2000s, were produced in two variants for US distribution, known as the M54 and M56. The M54 is the standard Low (or UL – Ultra Low) Emissions Vehicle (LEV or ULEV) version and the M56 is the Super Ultra Low Emissions Vehicle (SULEV) version intended for states that employs the most stringent vehicle emissions standards. In the US, the M56 was only produced in the 2.5 liter variant and only installed in the 325i, 325ci and 325it.
States that received 325i vehicles with the M56 engine may include; Arizona, California, Connecticut, District of Columbia, Maine, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington. However, don’t be surprised to find M54 models registered in these states … or …. M56 models in the other states.
Why should you know whether your BMW has an M54 or an M56 engine? When ordering engine, emissions, fuel system and some other parts, you will need to clarify if you have the M54 or the M56 engine. Failure to do so may very well result in the wrong parts being ordered.
So, how do you know which engine you have?
1) You can share the VIN with the BAVauto advisors, who can then use the VIN to verify the engine in your BMW.
2) Under the engine hood, the emissions control information sticker will note if the vehicle is a LEV or ULEV (M54) or SULEV (M56). The sticker is often on the underside of the hood itself.
3) The two engines are visually different when viewed under the hood. See images below: