Reconditioned SEAT Leon 1.9 TDI Gearbox

5 engine codes, two gearbox families: what determines the right choice for the Leon 1.9 TDI

On the Leon 1.9 TDI produced from 1999 to 2010, the gearbox fitted as standard was not uniform. Depending on the engine code — ASZ, BKC, BXE, BLS or BXF — and on the generation of the vehicle, the transmission is either a 5-speed manual or a 6-speed manual. These two families are not interchangeable: the casing, mounting points and gear ratios all differ. Before placing any order, the engine code stamped on the block remains the only reliable reference for identifying the exact part.

When rebuilding your own gearbox becomes the right option

Certain 1.9 TDI gearbox references — particularly on 6-speed versions — are now difficult to source on an exchange basis. If the original gearbox is mechanically salvageable (sound casing, intact shafts), rebuilding the customer's own unit is a practical alternative: the workshop reconditions the gearbox brought in and returns it to the same vehicle, avoiding any compatibility issues related to the axle ratio or the integrated speed sensor. This type of service is distinct from an exchange and is aimed specifically at cases where a replacement part is unavailable or difficult to identify.

Key points to watch on the 5-speed and 6-speed 1.9 TDI

The 5-speed manual fitted to the earlier generations (engine codes ASZ and BKC in particular) has well-documented wear on the 3rd and 4th gear synchromesh rings, which is common beyond 150,000 km under intensive mixed use. The 6-speed, introduced on later versions, is structurally more robust but prone to input shaft seal leaks. In both cases, a dull rumble in gear or difficulty selecting gears when cold are the most common symptoms indicating a gearbox that has reached the end of its life.