DL501 Transmission Solenoid and Internal Harness Kit

Solenoid pack and internal wiring harness for the 0B5 DL501 seven-speed S-tronic mechatronic unit, listed under OEM numbers 0B5398009C and 0B5398048D. The kit covers the solenoid assembly plus the internal harness that carries every signal between the external connector and the solenoids down in the valve body. Shipping weight is 4.27 pounds and it arrives in a 21.3 x 15.5 x 4.3 inch box, laid flat so the harness is not kinked in transit.

Fitment covers the longitudinal 7-speed front and all-wheel-drive S-tronic: Audi A4 and A4 Allroad 2009 and newer in 2.0L, 3.0L and 4.0L, A5 / A5 Cabriolet / A5 Sportback 2008 and newer in 2.0L, 3.0L, 3.2L and 4.0L, A6 2011, A7 2010 and newer 3.0L, and Q5 2008 and newer in 2.0L, 3.0L and 3.2L. Check the casting on your mechatronic before ordering. The DL501 is the longitudinal box; it is not the same unit as the transverse DQ250 or DQ200.

This is the repair people reach for before condemning a whole mechatronic. The internal harness sits in hot fluid for its entire life and the insulation eventually goes down, which shows up as intermittent solenoid circuit faults, gears that will not engage on a warm box, harsh or missing shifts, and drops into limp mode that clear on a cold restart. Because the fault comes and goes with temperature, it reads as an electrical problem in scan data even though the hydraulics are fine.

On the bench, drain the box and drop the mechatronic out of the case, then unplug the internal harness at the solenoid ends and lift the old solenoid set off the valve body. Lay the new harness in the same routing clips the factory used so it clears the pan rail, seat each solenoid connector until it clicks, and confirm the pass-through seal is square before the unit goes back up. Refill with the correct S-tronic fluid to the level plug at temperature; the box will not shift right if it is filled cold and left there.