The brief
The owner had been finding small ATF puddles under the gearbox area of the A4, and the shifts had grown noticeably harder, especially the first-to-second change under light throttle. The fluid level was clearly dropping.
That set of symptoms all points at the gearbox. ATF is the reddish-brown fluid the transmission uses for everything: lubrication, cooling, and the hydraulic pressure that makes the shifts. A leak takes the level down; a low level means the gearbox cannot build full pressure; and a gearbox short on pressure shifts harshly. Find the leak, top the fluid back up, and the shifts come back.
The diagnosis
On the lift, the leak traced cleanly to the ATF pan gasket, with a couple of the pan bolts having loosened over time. The ATF on the dipstick was below minimum, which lined up with the puddles and the hard shifts. And the pan itself had a small distortion at one bolt location, common ageing on these plastic pans.
So a re-torque alone would not have done it: a distorted seat will not seal even with new bolts torqued in. The pan needed replacing. And since the pan was coming off anyway, replacing the integrated filter at the same time, since it lives inside the pan, was the obvious call.
The work
Drained the ATF, dropped the pan, and cleaned both mating surfaces.
Fitted a new VAG-spec ATF pan with its integrated filter and a fresh seal, torqued to spec. Refilled with the correct ATF spec to the right level on a warm setpoint, because the level on these gearboxes is checked at a specific fluid temperature, not just by eye.
Then ran the gearbox adaptation routine on the scanner, so the transmission control unit re-learned a clean shift map rather than carrying on with the old worn one. That is the step that makes the shifts feel right again, not just stops the leak.
The outcome
Pan dry, no leaks. The shifts smoothed out across the rev range, including that first-to-second change under light throttle. Adaptation re-learned a clean map.
The A4 went home with the gearbox sealed and shifting properly again. For the owner, that means no more drips under the car, no more hard shift at low speed, and a transmission running on the right amount of clean fluid rather than slowly starving.
Catching an ATF leak at the puddle-and-hard-shift stage is the cheap version; running a gearbox low on fluid is the expensive one.
