Insignia rough running and fuel consumption

I drive an Insignia too and those symptoms sound familiar. I had something similar a few years ago, though not all the symptoms at once. Did you check the spark plugs?

Thanks. I haven't checked the spark plugs yet. Could you explain your experience and whether spark plugs were related?

The rough running and poor fuel economy were what I noticed first. The check engine light came on later. I'm no expert, but after checking forums, I took it to a workshop. They suspected the injectors. I suggest you do the same to prevent further damage.

I appreciate the advice. My mechanic agreed, and a thorough inspection found a defective fuel injector causing the rich running. Replacing the injector for 515€ fixed it. The car runs perfectly now.