Presage diesel smoke preheating lamp issue

That sounds awfully familiar. I've got a Presage too, diesel as well. Those symptoms – the preheating lamp, the engine light, and the smoke – scream glow plug control unit to me too. Have you run a diagnostic test yet? That's the first thing I'd recommend. Any luck checking the heating element itself?

Yeah, I ran a basic OBD-II scan, and it threw a generic code related to the glow plug circuit. But here's the thing: the plugs themselves seem fine when I tested them individually. So, I suspect it's not the heating element itself, but the control unit, or the wiring to it. What exactly did you replace when you faced a similar issue?

Understood. If the glow plugs are testing okay, then yes, focus on the control unit and its connections. In my case, I went straight to a workshop. They diagnosed it as a defective glow plug control unit and some corroded connectors. Replacing those sorted everything out.

Right, that confirms my suspicions. Thanks. I think I'll bite the bullet and take it to a shop. I'm estimating about 95€ for the repair. Hopefully it's just the control unit and not something nastier. Thanks for the advice; it’s good to have a starting point.