LandCruiser preheating lamp and smoke issue

Sounds familiar! I had similar symptoms on my old Saab 9-3, preheating light staying on, engine light popping up. Could it be the glow plug relay or a dodgy temperature sensor messing with the preheating cycle? Did you check the fault codes?

Thanks! Could you elaborate on how the glow plug relay or temperature sensor might be connected to the control unit's malfunction and the smoke? Are there tests I could perform to isolate the cause before replacing parts?

Well, on the Saab the relay was basically stuck, telling the glow plugs to keep heating even when the engine was warm. The ECU got confused, hence the light. I didn't mess with diagnostics myself back then. If you're seeing smoke too, and suspect glow plugs, I'd just take it to a trusted shop. Sounds like it's beyond a simple DIY fix. I ended up with a similar repair cost anyway.

Thanks for the insights. Considering the potential complexities and the smoke, I agree that professional diagnostics is the best course of action. I'm scheduling a workshop visit. It was a faulty control unit and the repair was 95€.