Persistent Audi S4 Turn Signal Failure After Mechanic Work

Had a similar electrical fault on an Audi S5 2010. The turn indicator issue matched your symptoms exactly, with persistent failures on the right side. The signal lamp kept showing errors despite replacing bulbs. The root cause was not the turn signal bulb or flasher relay. A damaged wiring harness connector near the front right headlight assembly was causing intermittent electrical connection issues. The previous work likely disturbed or stressed these connections. The fix required: Complete inspection of the wiring harness, Replacement of corroded connector pins, Reseating all electrical connections in that area, Testing continuity across the entire indicator circuit This was a serious electrical system issue that could have led to complete turn signal failure if left unaddressed. The connector problem was causing voltage drops, triggering the fault codes in the speedometer cluster. Would recommend having the wiring harness and all connections thoroughly checked, particularly around areas where previous electrical work was done. These symptoms rarely resolve with just bulb replacements when there are concurrent instrument cluster warnings.

Thanks for sharing your experience with the faulty connector. Going through something very similar with my S4 right now. After 6 months of annoying turn indicator problems, I finally got it looked at last week. The mechanic found significant corrosion in the wiring harness exactly where you described. Can you recall the repair costs for your electrical fault fix? My S4 is still at the shop and they mentioned possible additional issues with the headlight assembly wiring. Wondering if anything else came up during your repair that I should watch out for? The lamp replacement attempts and new flasher relay were clearly just treating symptoms rather than the root cause, as you mentioned. Good to know about checking those harness connections near previous repair work.

After getting my vehicle fixed, I can confirm the total repair cost was 95 Euro for resolving the defective turn signal lamp issue. The mechanic identified and fixed a faulty cable and plug connection, which matched exactly what I experienced with my S4 previously. The automotive lighting system now works flawlessly. No additional problems surfaced during the repair, unlike what your shop suggested about potential headlight assembly complications. My signal lamp operates perfectly after they addressed the connection issues. Looking back, all those bulb replacement attempts were indeed just masking the real problem. The electrical fault was clearly tied to those corroded connector points. The repair cost was reasonable considering the diagnostic work needed to pinpoint the exact connection failure. Good thing you had it properly checked instead of continuing with temporary fixes. These electrical gremlins typically dont resolve themselves and often get worse if left unchecked. The symptom of a persistently failing turn indicator despite new bulbs is almost always pointing to wiring or connection problems.

Thanks for the detailed input. Wanted to share how my repair turned out. Finally got my S4 back from the shop yesterday. The mechanic traced the turn signal problems to exactly what was discussed, corroded wiring connections near the front right headlight. The automotive lighting harness had significant wear where it connects to the indicator light assembly. Total repair came to 140 Euro which included: Replacing damaged wiring sections, New connector set, Full system diagnostic, Labor costs The broken lens theory and all those bulb replacements were definitely a waste of time and money. The turn indicator now works perfectly with no more error messages in the speedometer. A bit frustrated it took so long to properly diagnose, but relieved to have the actual electrical fault fixed rather than just treating symptoms. No other issues were found with the headlight assembly wiring, thankfully.