Audi electric steering rack, post fitting initialisation guidance.

The angle sensor that is utilized for all steering related functions is the angle sensor in the steering column, the steering rack does not contain an angle sensor , so when we test a rack it is impossible for us to synchronize the angle sensor as we do not have your steering column angle sensor output to use, this can only be done once the rack is fitted back into the car and then gets a steering angle sensor output from your column .
If the output from your steering angle sensor is either not correct because the column was rotated out of position or the rack was fitted when not in the zero straight ahead position, then the rack will realize that there is an inconsistency and will not allow the lock stop learning to proceed.

In order to diagnose why the lock stop learning will not complete you must check the following:
1 ; if your vehicle has standard non dynamic steering then there should be 2.9 turns from lock to lock, if your vehicle has Dynamic steering then there should be 2.5 turns lock to lock, so check that you have the correct number of turns.

2; Make sure that the steering wheel is straight when the road wheels are straight and that the tie rods are equally adjusted on both sides when the front wheel alignment is done, a short drive to confirm that the car drives in a straight line with the steering wheel straight.

3; If the 2 above parameters are correct the you will need to attach a scanner capable of displaying a live data reading from the angle sensor in Module 16 which is your steering column, do not try to read the angle sensor output from the rack.
with a scanner connected and the steering angle sensor live output showing , check that when the steering wheel is straight the output is close to zero degrees and then watch the angle sensor reading as the steering is turned towards the end of either lock, the reading should consistently count up in degrees until the end of lock, hold it at the end of lock and check the reading approximately 522degrees +- 5degrees if non dynamic and 450 degrees if dynamic, then repeat the process on the opposing lock and make a note of the readings again, the two end of lock readings should be within 20 degrees.

4; If all of the above is followed and corrected where necessary and if the steering angle sensor is outputting correctly the the lock stop learning can be performed, there is no need for a scanner when completing the end stop learning , the most common reason for it to fail is an inconsistent or incorrect output from the steering angle sensor in the column.