Audi A2 No-Start: Terminal 15 Voltage Drop Issue

Had the same starting issue on a 2006 Audi A3 1.6L. The car would not start and showed similar error codes. The power supply to the ignition switch was compromised due to a deteriorated wiring harness near the steering column. The starter solenoid was receiving inconsistent voltage because several wires had worn through their insulation, causing intermittent connections. This created a voltage drop at the battery terminal connection points. These electrical gremlins often get misdiagnosed as simple ignition switch failures. The complete repair required: Replacing the main wiring harness section, Installing new battery terminal connectors, Testing all ground connections, Verifying starter solenoid operation This was a serious electrical system issue that could have left the car stranded at any time. The car would occasionally start fine, then refuse to start hours later, making diagnosis tricky. Would strongly recommend having a qualified shop perform complete electrical testing rather than just replacing parts. A proper diagnosis using voltage drop testing across all major connections will pinpoint the exact failure point in the circuit. This prevents costly trial-and-error repairs.

Thanks for sharing those details about your A3. My A2 seems to have similar symptoms to what you described, especially the intermittent starting. Had mine fixed last month but wondering if I should have the wiring harness checked too since the car wont start reliably again. Did you remember roughly what the total repair cost was? Also curious if youve had any other electrical gremlins pop up since getting it fixed? The power supply issues you mentioned make me think I should have the battery terminal connections inspected while theyre at it.

Good to report back on this! Since taking my A3 to a qualified shop, they traced the Terminal 15 ignition positive interruption and fixed it completely. The repair cost was 95 Euro for addressing the faulty cable connection, which is much less than replacing the entire wiring harness. The key was proper diagnostic testing, they used voltage drop testing across the fuse box and all critical connection points. This targeted approach saved money compared to replacing parts unnecessarily. No electrical issues have occurred since the repair. However, your case sounds very similar to mine, so I would recommend having them check: All battery terminal connections, The starter solenoid wiring, The complete ignition switch circuit, Any signs of wiring harness wear near the steering column Getting a thorough electrical diagnosis now could prevent being stranded later. The intermittent starting you describe often points to connection issues rather than failed components.

Thanks for all the great advice. I just got back from the shop and wanted to share how it went. Took it to a different mechanic who specializes in electrical diagnostics this time. Sure enough, they found a significant voltage drop in the circuit when testing the connections. The main culprit was corroded wiring near the relay switch, plus some worn battery terminal connections that were causing inconsistent power supply to the ignition system. Total repair came to 180 Euro, which included cleaning all connections, replacing the damaged wiring section, and installing new battery terminals. The thorough voltage testing really made the difference, no more intermittent starting issues since the repair. They also checked the entire fuse box and surrounding wiring harness while they were at it, which gave me peace of mind. Much better experience than my previous repair attempt that didnt solve the root cause. Really glad I followed the advice about getting proper electrical diagnostics instead of just replacing parts. The car starts perfectly now, every time. Thanks again for pointing me in the right direction with this!