Audi A3 Diesel Won't Start: Power Supply Glitch Fix

As an Audi A6 2010 TDI owner, I faced nearly identical symptoms. The clicking sound from the starter solenoid with no start typically indicates a wiring harness issue rather than a full starter failure. The fix in my case involved: Corroded battery terminals causing poor connection, Damaged relay switch in the main fuse box, Loose ground cable connection Key points to check before visiting a garage: 1. Clean both battery terminals thoroughly 2. Check the main fuse box for any obvious loose connections 3. Test voltage at the battery while attempting to start 4. Inspect the ground cable connection to the chassis This was a moderate repair job requiring specialized diagnostic equipment to properly trace the power interruption. The car won't start issue was ultimately traced to a combination of the damaged relay switch and corroded connections. These electrical issues can be tricky to diagnose without proper testing equipment, but checking these basic connections might save you a garage visit. If basic checks don't resolve it, professional diagnosis is necessary as it could affect other electrical systems over time.

Thanks for sharing your experience. I had very similar symptoms with my A3 2015 last winter. The ignition switch would only work intermittently and the circuit break in the fuse box turned out to be the main culprit. Your solution path sounds spot on and quite similar to what my mechanic did. The car won't start issue cleared up completely after fixing those electrical connections. Would you mind sharing what the total repair cost was in your case? Also curious if youve had any related electrical issues pop up since the fix?

Had my A6 checked by a certified mechanic last week. The ignition positive signal on Terminal 15 was indeed interrupted, just as suspected. The repair focused on fixing a faulty cable connection linked to the ignition switch. The total cost came to 95 Euro for parts and labor. Since fixing the voltage drop issue at the connection point, the car starts perfectly every time. The mechanic also inspected the entire fuse box and battery terminal setup while diagnosing the problem. No related electrical issues have occurred since the repair. The relay switch and all other connections are now working as they should. Having a professional trace the exact source of the power interruption was worth it, as these electrical problems can be quite complex to diagnose properly.

Thanks for the advice. After visiting my mechanic yesterday, here is how it went down: The main issue was exactly what you described, an electrical fault in the wiring harness near the steering column. The mechanic found the relay switch had water damage from a small leak, causing intermittent connection failures. Total repair came to 180 Euro including: New relay switch, Partial wiring harness replacement, Labor costs, Full electrical system check The car starts perfectly now. They also found and fixed a loose ground cable while doing the work, which explains the battery drain issues I had been seeing. The fuse box was inspected and cleaned as a precaution. Really glad I asked here first, helped me understand the likely problem and avoided getting overcharged. No more car won't start issues since the repair was done. Thanks again for helping point me in the right direction.