Seat Exeo Lighting System Fault

Sounds like a pesky electrical fault. Given the error message and lighting issue, a defective cable or plug connection is certainly a strong possibility, especially affecting the indicator light. Have you checked the bulb itself? Although it seems unlikely to be the sole cause considering the error message, it's always good to rule out the simple things first. Also, inspect the connector and wiring leading to the signal lamp for any signs of corrosion or damage. Sometimes a bit of contact cleaner can work wonders if it's just a slightly corroded connection. Has the issue only occurred on one side of the vehicle?

I checked the bulb, it appears fine. Could you elaborate on how to best inspect the connector and wiring? What exactly should I be looking for?

Since the bulb seems okay, focus on the connector and wiring. Look for any visible damage to the wires – cracks, fraying, or exposed copper. On the connector, check for bent or corroded pins. Corrosion often appears as a greenish or whitish deposit. Gently try wiggling the connector while the indicator is on to see if that causes any flickering or change in behavior, which would indicate a loose connection. Given the electrical fault and associated error codes, it is likely beyond a simple bulb replacement or connector cleaning. I recommend a visit to a workshop.

Thank you for the information and confirmation. The workshop confirmed your suspicion – defective cable and plug connection. Repair cost me 95€.