Audi S5 Multiple System Failures Points to Clutch Switch

I had a similar electrical fault on my 2012 Audi S4 last year. With some experience working on Audis, these symptoms often point to a safety switch malfunction. The car stalling and multiple system failures you describe match exactly what happened with mine. The clutch switch and associated safety mechanism were giving false signals, causing the car to think the clutch wasnt properly engaged. My workshop found a damaged wire connection at the clutch pedal assembly. The repair involved replacing the wiring harness connector and the safety switch itself. Total cost was 95 Euro, mostly labor since the parts were relatively inexpensive. Before you proceed with repairs, could you share: Is this a manual or automatic transmission? Does the issue occur consistently or intermittently? Are there any specific conditions when the problem appears (cold starts, after driving)? What exact error code is stored? This information would help confirm if your issue matches what I experienced. The safety switch system on these models is known to cause electrical faults that can affect multiple systems simultaneously.

Thanks for the detailed response. My car has an automatic transmission with 24199 KM on the odometer since the last service. The ignition problem occurs consistently every time I try to start the car now. The gear selector display goes completely dark before any starting attempt. When attempting to start, there is zero response from the starter motor. The stored error code is P0803 which relates to the clutch position control circuit. The issue started suddenly during normal operation with no prior warning signs. The car was running perfectly fine until I parked it at ambient temperature, and when I returned, all these electrical faults appeared simultaneously. Given this additional context about the transmission type and error code, Im wondering if this still aligns with your experience or if I should be investigating a different root cause?

Based on your automatic transmission setup, I need to revise my initial assessment. While the symptoms are similar, the root cause is likely different from what I experienced. In automatic Audi models, these symptoms typically indicate a fault in the gear selector safety mechanism rather than a clutch switch. The P0803 code, though clutch-related, can sometimes be triggered by the gear selector position sensor in automatic transmissions. My automatic S4 had a similar electrical fault pattern. The fix involved: Replacing the gear selector position sensor (180 Euro), Repairing corroded wiring connections at the selector assembly, Resetting the transmission control module The safety switch system in automatic models is more complex than manual versions, integrating multiple position sensors to ensure proper gear engagement before allowing ignition. When this system fails, it causes the same cascade of issues: no starter response, blank display, and disabled cruise control. Some questions to help narrow down the diagnosis: Can you move the gear selector freely? Does the brake pedal feel normal when pressed? Are there any warning lights on the dashboard besides the gear display? The zero response from the starter strongly suggests a safety interlock issue rather than a transmission problem.

Thank you for the follow-up information regarding the automatic transmission. The P0803 error code combined with the gear selector and starter issues makes me more confident about the diagnosis path. I just checked the brake pedal, and it feels completely normal with proper resistance. The gear selector moves freely between positions, but the electronic display remains dark regardless of position. Besides the blank gear display, there are no other warning lights on the dashboard. The consistent nature of the ignition problem and the immediate onset of all electrical symptoms point strongly toward your suggestion of a gear selector position sensor fault. This matches the behavior pattern exactly, parking the car in normal conditions and returning to find multiple system failures. Given the error code and symptoms align closely with your experience, I think I will proceed with having the gear selector position sensor checked first. The price point of 180 Euro for the sensor replacement seems reasonable compared to the diagnostic uncertainty of testing multiple components. Would you recommend getting the wiring connections inspected at the same time, since corrosion was part of your repair solution? Im trying to avoid multiple repair visits if possible, and it sounds like the wiring could be contributing to these car starting issues.