Mondeo rough running and smoke

Sounds suspiciously like a defective EGR valve. I had similar symptoms on my Mondeo – reduced power, engine light, and even failed an emissions test. Have you checked the valve itself for excessive carbon buildup or if it's jammed?

EGR valve, huh? Interesting. Where exactly is it located, and is it something I could reasonably check myself? I'm no mechanic, but I'm not afraid to get my hands dirty. Any tips on identifying a jammed valve?

While some experienced DIYers tackle EGR valve replacement, the location varies depending on the specific engine configuration. Given the symptoms you describe – rough running and smoke – alongside the check engine light, it’s likely more than just a simple cleaning job. Consider taking it to a reputable workshop. A faulty EGR valve can seriously impact your vehicle emissions and cause further damage if left unaddressed.

Workshop diagnosed a defective EGR valve, just as you suspected. Repair came to 355€. Appreciate the heads-up; saved me a lot of pointless fiddling!