Seicento oil level warning light

Sounds like a faulty oil level sensor or wiring issue. Have you checked the wiring and plug connection to the sensor itself? A loose or corroded connection can cause intermittent signals and trigger those warnings. It's a common problem. Can you read out the error code?

I had a quick look at the sensor and the connector seemed okay, but I didn't really dig deep. Where exactly should I be looking for corrosion or damage? I'm getting a P0196 code.

P0196 confirms the oil temperature sensor range/performance issue, which often goes hand-in-hand with the level sensor on these. Double-check the connector pins for any green crustiness. Also, inspect the wiring harness a few inches back from the connector for any breaks or chafing. If the wiring looks good, the sensor itself might be failing. I advise you to get it checked out by a professional workshop.

Thanks for the advice. I took it to a shop, and you were spot on. Turns out it was a corroded connector. They cleaned it up and replaced a short section of damaged wire. Cost me 95€, but at least it's fixed!