Peugeot 4007 Glow Plug Issue

Yeah, sounds like a glow plug. Had similar symptoms on my old car. Is it hard to start when it's cold? And are you noticing any difference in fuel efficiency?

It does seem a bit harder to start when the engine is cold. I haven't really paid attention to fuel efficiency. Could a faulty glow plug really affect fuel consumption that much?

Hard starts plus the light staying on, yeah, almost certainly a glow plug. And yes, it can impact fuel efficiency a bit since the engine combustion won't be optimal, especially during cold starts. I wouldn't drive too long with it. I'd recommend getting it checked by a workshop.

Thanks for the advice! I took it to a workshop, and you were spot on – defective glow plugs. Cost me 440€ to get them replaced.