Reconditioned BMW 3 Series 2.0d Gearbox

Three engine codes in fifteen years: the evolution of the BMW 3 Series 2.0d gearbox from 2005 to 2019

The 3 Series 2.0d spans a long period during which BMW successively adopted three four-cylinder diesel units: the M47D20, used until the mid-2000s, the N47D20, introduced with the E90/E91/E92/E93 generations from 2007, and then the B47D20, fitted to the F30/F31 in its later life and to the G20 from 2018. Each of these units is paired with a distinct gearbox reference within the six-speed GS6 family, making the engine code stamped on the block essential for accurate identification.

GS6 references that are not interchangeable across generations

The references shown in this collection — GS6-17DG, GS6X37DZ, GS6X45DZ, GS6-45DZ — correspond to different internal ratios and torque ratings depending on the power output of the associated engine. The GS6-17DG is typically fitted to the 143 hp to 150 hp variants, whilst the GS6X45DZ and GS6-45DZ accompany higher-torque engines. A single production year may therefore use two incompatible references depending on the exact power output of the 2.0d. The alphabetical suffix of each reference also identifies the internal version of the gearbox: two gearboxes sharing the same root code may differ in their synchromesh or casing.

Key points to watch with the N47D20

The N47D20 unit, widely used between 2007 and 2015, is known for a weakness in its timing chain on the gearbox side. This well-documented fault can cause vibrations and noises that are sometimes wrongly attributed to the gearbox itself. Before placing any order, it is therefore worth confirming that the symptoms are coming from the transmission rather than the engine. On the gearbox side, typical wear on these 2.0d units affects the lower-gear synchromesh rings and, on high-mileage examples, the primary shaft bearings.