Audi S7 No-Start: Terminal 15 Ignition Issue Alert

I had a similar issue with my 2014 Audi S6 last summer and can share some medium-level experience with starting problems like this. When my car won't start, I initially suspected the starter solenoid, but it turned out to be a corroded wire connection at the ignition switch harness. The symptoms were identical, power to the switch but no response when turning the key. After checking the basic power supply points, my workshop found that one of the main connector plugs going to the ignition switch had developed corrosion, causing an intermittent connection. They cleaned the contacts and replaced the damaged portion of the wiring. Total repair cost was 95 Euro including diagnostic time. Before suggesting more specific solutions, could you provide: Have you noticed any intermittent starting issues before this? Does the instrument cluster light up normally? Are there any clicking sounds when turning the key? Have you checked the fuse box for blown fuses related to the ignition system? This would help determine if your issue matches what I experienced or if it might be something different in the starting circuit.

Just had my latest service at 141795 KM, and wanted to update that we found the root cause. The circuit break in the main relay switch was causing the no-start condition. The workshop traced it to a failing power supply module that was interrupting the terminal 15 signal. They also found minor damage to the wiring harness near the firewall, likely from heat exposure. Total repair cost was 280 Euro including parts and labor. The car starts perfectly now with no error codes. Can confirm this is a known issue with these models, worth checking the relay module first before diving into more complex diagnostics.

Thanks for the update on your S7 starting issue. That matches exactly what happened with my S6 after we dug deeper, the symptoms were nearly identical. The power supply module failure affecting the relay switch is actually a common weak point in these models. While my initial diagnosis focused on the corroded ignition switch connection, the workshop later found the same relay issues you described when the problem returned a few months later. The wiring harness damage near the firewall is particularly interesting, had the same heat-related deterioration on mine. When the car won't start, these seemingly minor wiring issues can cascade into bigger problems, especially when they affect the terminal 15 circuit. For reference, my complete fix required: New power supply module, Relay switch replacement, Wiring harness repair, Full system diagnostic reset Total cost ended up at 295 Euro, so pretty close to your repair bill. Going straight to checking the relay switch and power supply module would have saved diagnostic time. Good to document these fixes for others who might face similar starting problems.

I see the repair confirmed exactly what several S6/S7 owners experienced. The failing power supply module really seems to be the common denominator in these no-start conditions. Having the workshop check the relay switch first definitely saved time compared to testing multiple components. The wiring harness damage near the firewall appears in many cases too. My 280 Euro repair seems fair compared to similar fixes, though some paid over 300 Euro for the same work. The terminal 15 ignition positive interruption ended up being a textbook symptom of the faulty relay switch and power module combo. For anyone searching the forum later: When the car wont start, checking the fuse box is still step one, but having the workshop examine the power supply module and relay switch connections should be an early priority if fuses look good. These components failing seems to be a known weakness worth documenting. Glad I could share my experience and get confirmation that this is a repeatable issue. Getting a complete diagnosis and fix means no more starting problems or error codes.