Some early Seat Leon 1P Facelift cars with Media-In functionality (AUX, USB & iPod support) suffer from a problem where the mid-tones on the left channel are missing when listening to analog audio through the AUX input, which includes listening from an iPod with the iPod adapter cable. This can be resolved in a couple of minutes by replacing the old AUX port with a new and fixed revision.
The problem is a faulty circuit board in the combined USB/AUX port (CUP) panel, where the lines of the 3.5mm stereo plug are incorrectly wired. The left channel is flipped with the right channel, and even worse, the right channel is flipped with ground.
To solve this problem, you need to replace the original panel (part# 1P0035726 GB1) with a new revision that you can order from your dealer under part# 1P0035726A GB1 (make sure it’s the revised “A”-version) for about 35€. This can be done relatively easily and quickly, which I’ll show you step by step:
Step 1 (Picture 1): Remove the right cover of the center console by pulling down the underlapping part marked with the orange arrows until it snaps out. Then, pull at the yellow circled area to free it from two plastic clips.
Step 2 (Pictures 2-4): Insert a flat screwdriver into the magenta colored hole (2a). You need to press and release a hook on the panel that is located behind the green circled area (2b). The hook can be seen in picture 4 and locks the panel into the center console. You don’t need to apply strong force.
Step 3 (Picture 5): Once the hook is released, pull out the panel starting from the right edge. Again, do not brute force, it comes out very easily.
Step 4 (Picture 6): Unplug the two cords from the panel by releasing their locks, plug in the new panel and put everything together the other way round.
Enjoy your newly gained high fidelity!