Peugeot 407 Torque Converter Issue

That sounds familiar! I own a Peugeot 407 as well and experienced something very similar last year. The symptoms you describe match mine almost exactly: engine surge, rough shifting, and eventually the warning lights. Have you noticed if it happens more often under specific conditions, like when the engine is cold or after driving for a long time?

That’s interesting. Now that you mention it, it does seem worse when the engine is warmed up. When it's cold, it's still not great, but definitely smoother. So, was it definitely the torque converter in your case? How much did it set you back?

Unfortunately, yes, it was the torque converter. After some diagnostics, the workshop confirmed the diagnosis, pointing to a defective automatic transmission converter. I'm afraid that the repair bill was quite high. Given the grinding noises you're hearing, I would strongly recommend getting it checked out by a professional ASAP to avoid further damage.

I bit the bullet and took it to my local mechanic. You were spot on. It was the torque converter, and it cost me 2120€ to get it replaced! At least it's running smoothly again. I appreciate you sharing your experience; it helped me prepare for the worst!