Hyundai i10 Diesel Power Loss Smoke

Sounds familiar. I had a similar issue with my old Renault Megane diesel. Reduced power and smoke are classic symptoms of DPF problems. A DPF is a filter designed to remove soot from the exhaust gases of a diesel engine. Have you had a vehicle inspection to check for any stored fault codes? Sometimes the sensors can be slow to trigger the light, but the code will still be there.

Even without the engine light, could there still be a fault code? Is it worth getting it checked even if everything seems normal otherwise? Is the DPF definitely the culprit, or could it be something else entirely?

Yes, definitely get it checked for codes. I drove mine for a few weeks before the light came on, and those weeks cost me in lost fuel efficiency. It could absolutely be something else, but those symptoms are DPF until proven otherwise. When my Megane had those issues and that mileage, it turned out I needed a new DPF and associated sensors. Check with a mechanic, but be prepared that you might have to replace the whole unit.

I'll book it in for a proper vehicle inspection and see what the fault codes say. The mechanic confirmed that it's a defective DPF. He quoted me 1550€ for the whole repair.