Insignia Incorrect Fuel Composition Error

That sounds frustrating. I had a similar issue with my old Volvo a while back, though mine was a diesel. Check engine light, rough idling, the whole nine yards. For me, it turned out to be a dodgy connection in the fuel system. Have you checked the cables and plugs going to the fuel sensors? It might be worth a look before you start thinking about expensive repairs.

When you say 'dodgy connection', what exactly should I be looking for, like loose wires? And where exactly are these fuel sensors located? I'm not super mechanically inclined, so any extra detail would be a huge help!

Yeah, exactly. Look for anything obvious – loose connectors, corroded pins, damaged wires. In my Volvo, it was a connector that had come loose. As for the location, it really depends on the Insignia's setup. Honestly, if you're not comfortable poking around, it might be best to take it to a workshop. I ended up doing that, and they sorted it out pretty quickly. It's worth it for the peace of mind.

I took it to my local mechanic, and you were spot on. It was a defective cable connection. They fixed it for 95€, and it seems to have solved the problem. Really appreciate you pointing me in the right direction!