Peugeot 607 Preheating Lamp Issue

I had a similar problem with my 607. The constant preheating light is a real pain. In my case, it was indeed related to the glow control unit. Did you notice any vehicle stalling, especially when the engine is cold? A defective control unit can cause the engine not to preheat, which results in vehicle stalling. Also, can you check if the engine light is constantly on or if it flashes?

Thanks for the info! No stalling yet, thankfully. The engine light is constantly on, not flashing. It's only started happening since the preheating light issue began. I'm trying to avoid taking it to a garage if it's a simple fix, but I'm not sure where to start.

Okay, a constant engine light, along with the preheating issue, does point towards the glow control unit. Given that you're seeing smoke on acceleration too, it's possible the engine isn't getting the correct fuel mixture due to the faulty preheating. I'd advise getting the control unit professionally checked. I know it's annoying, but it could prevent further damage. I ended up taking mine to the workshop.

Thanks for your help. I took it to the garage, and you were right – it was the glow control unit. They said a cable was defective. Repair cost me 95€, and it seems to have solved the problem.