How to Read BMW Engine Codes

BMW engine codes look like random letters and numbers, but they follow a logical system. Once you understand it, you can decode any BMW engine at a glance.

The Format: [Letter][Number][Number][Letter/Number]

Example: N54B30

First Letter — Origin

• M = Motorsport-era (pre-2001): M50, M54, M62
• N = New generation (2001-2015): N52, N54, N55, N63
• B = Current modular (2013+): B38, B48, B58
• S = M Division sport: S50, S54, S55, S58, S63, S65

First Number — Cylinder Count

• 3 = 3 cylinders (B38)
• 4 = 4 cylinders (N42, N46, N20, B48)
• 5 = 6 cylinders (M50, N52, N54, N55, B58)
• 6 = V8 (M60, N62, N63)
• 7 = V12 (N73, N74)
• 8 = V10 (S85)

Note: For inline-6, BMW uses "5" not "6" — this is a historical convention.

Second Number — Revision

Higher = newer revision within the same family:

• N52 → N54 → N55 (all 3.0L inline-six, each a new design)
• B48 (4-cylinder) is the same generation as B58 (6-cylinder)

Letter After — Fuel Type

• B = Benzin (petrol/gasoline): N54B30
• D = Diesel: N47D20
• K = Alternative fuel (hydrogen, etc.)

Final Numbers — Displacement

• 30 = 3.0 liters: N54B30
• 20 = 2.0 liters: N20B20
• 44 = 4.4 liters: N63B44
• 15 = 1.5 liters: B38B15

Quick Decode Examples

Code	Meaning
N54B30	New-gen, 6-cylinder, petrol, 3.0L
B58B30	Modular, 6-cylinder, petrol, 3.0L
S55B30	M Sport, 6-cylinder, petrol, 3.0L
N47D20	New-gen, 4-cylinder, diesel, 2.0L
N63B44	New-gen, V8, petrol, 4.4L
S65B40	M Sport, V8, petrol, 4.0L
B38B15	Modular, 3-cylinder, petrol, 1.5L

Suffixes

Some engines have additional suffixes:

• TU = Technical Update (revised version): N63TU
• O1 = Variant 1: B58B30O1 (TU1 revision)
• S0/S1 = Sport variant: N57D30S1 (triple-turbo)

Now you can decode any BMW engine code on sight.