DSG6 REPAIRS
The six-speed ‘wet clutch’ DSG gearbox (code DQ250) differs considerably from the newer DSG7 (DQ200). Instead of a separate oil supply, the DQ250’S Mechatronics unit uses the same oil as that which lubricates the gearbox internals and cools the wet clutches. This therefore exposes the Mechatronics to greater temperature variations and a higher risk of contamination, compared to the DSG7. As some DIY repairs are possible, here is an overview of how to remove it from the gearbox without damage. We emphasise, however, that the following steps were not conducted on ECU Testing’s premises.
B1 Unlike the DSG7, you have to remove the Mechatronics unit’s sump cover in order to access the bolts that secure it to the transmission. However, drain the gearbox oil first.
B2 Prise the cover gently from the gearbox casing; do not forget to check that the main electrical socket (and associated wiring on the vehicle) is in good condition, because it is vulnerable to damage.
B3 With the cover removed, the Mechatronics unit's valve body is revealed. Unlike the DSG7, there's no dangerous residual pressure stored in the system. When they fail, the fault code relates to the pressure adaptation being out of limit.
B4 Disconnect the wire that leads from the Mechatronics unit to the input speed sensor. This measures the speed of the clutch drum. Be wary of breaking the plastic connector.
B5 Unscrew the bolts that hold the Mechatronics to the gearbox casting. Like the DSG7, you have to pull it away from the transmission straight, because tilting it risks damage.
B6 Clumsy removal risks snapping the plastic reverse shaft speed sensor extension, which goes deeper into the gearbox. Should it break, you will have to seek a new Mechatronics.
B7 You can remove the adjacent oil pump cover (although it is not completely necessary), enabling you to help manipulate the reverse shaft speed sensor as you extract the Mechatronics.
B8 CM’S February 2016 issue contained more detailed information on DIY diagnostics and repair procedures on the DSG6 but, like the DSG7, issues with the PCB should be left to specialists.