Smart Roadster Dead: No Start, No Crank, Silent Key Turn

Had the same starting issue on a 2000 Smart City Coupe last year. Complete electrical failure symptoms pointed to battery connections, not ECU issues as initially suspected. The main battery terminals showed severe corrosion under the plastic covers, causing intermittent connection loss. This can trigger brief engine fault warnings before complete failure. When the connection degrades enough, you get exactly what you describe, total silence when turning the key. Remove the terminal covers and inspect for white/green buildup. Clean the terminals with a wire brush and ensure the cables are properly tightened. Loose or corroded connections often get misdiagnosed as ECU failure on these models, leading to unnecessary repairs. If cleaning the terminals does not resolve it, have the battery tested. A failed battery can show similar symptoms, but the terminal connection issue is more common with Smart models of this age range. This is generally not a serious repair when caught early, but ignoring it can lead to electrical system damage. Important to address it promptly to prevent potential ECU strain from voltage fluctuations.

Thanks for sharing your experience. After trying your suggestions, the battery terminal cleaning fixed it right away. Engine surge and stalling issues completely disappeared after proper terminal maintenance. Just wondering, what did the repair end up costing you? And have you experienced any other engine diagnostics issues since fixing those connections? Always good to know what to watch out for with these Smarts.

Thanks for asking about the costs. The repair bill came to 155€ for fixing the loose cable connections at the battery terminals. Looking back, the engine stalling and starting problems were definitely caused by those faulty connections, not an ECU issue like I first feared. Since getting the battery connections properly fixed by the mechanic, the check engine light hasnt come back on at all. The engine software is running smoothly with no diagnostic codes showing up. It really proved that simple electrical connection problems can mimic more serious engine control issues on these models. Been driving the car for over a year now without any starting problems or engine diagnostic warnings. Regular battery terminal checks have become part of my maintenance routine to prevent similar issues from developing again.

Just wanted to update on how it all turned out. Took the car to my local mechanic after cleaning those terminals myself. They did a full electrical system check for 80€ to be on the safe side. Turns out you were spot on, the battery connections were the main culprit. The mechanic also found some engine software readings that were a bit off due to the poor power supply, but these normalized once the electrical system was stable again. No more check engine warnings or starting problems since the fix. The engine surge issues I was getting also cleared up completely. Really glad I checked the simple stuff first instead of jumping straight to expensive ECU diagnostics. Still keeping an eye on those terminals now as part of regular maintenance. Definitely learned my lesson about basic electrical checks before assuming the worst.