Peugeot 408 injector fault

That 'reset quantity drift compensation' error on a diesel usually does point to injector problems. Have you noticed any changes in fuel consumption or engine performance besides the rough running? Also, has the car had any performance tuning or modifications done to the fuel injection system? Those can sometimes mess with the injector calibration and throw that code.

Fuel consumption seems normal, but performance is definitely down. No performance tuning, it's all stock. When you say injector problems, are we talking replacement or is there a chance a cleaning or recalibration could fix it? Is there a way to check the car sensors to see if that could be it?

Cleaning or recalibration might work in some cases, but with that mileage and the specific error, a defective injector is the most likely culprit. Unfortunately, diagnosing individual injectors usually requires specialized equipment. I'd recommend taking it to a workshop. They can run proper diagnostic tests and confirm which injector is faulty. Saved me a headache on my old Citroen a while back.

Thanks, I appreciate the input. Took it to the workshop, and you were spot on. Faulty injector, they replaced it. Cost me 515€, but the engine's running smooth again.