Engine Number

The engine number "engine code" and "serial number" are located at the engine/transmission joint.

Fig 1: Locating Engine Number ("Engine Code" And "Serial Number")

Courtesy of AUDI OF AMERICA, LLC

The engine code is also printed behind the oil filter on the cylinder block.

Vehicles with Four Digit Engine Codes 

Four digit engine codes beginning with the letter "C" are used. The first three digits describe the mechanical structure of the engine and are still stamped on the engine, as before. The fourth digit describes the engine output and torque and depends on the Engine Control Module (ECM). Four digit engine codes are found on the type plate and vehicle data label. It can also be read via the ECM.