Mercedes B Klasse Diesel Jerking and Check Engine Light

Sounds like a vacuum leak to me. I had a similar issue with my old Opel, though the symptoms weren't quite as pronounced. Jerky acceleration, yes. Rough running, yes. Check engine light, definitely. The manifold sensor was going crazy. Have you checked for scorching or cracks on the car manifold? That could be your culprit. Is the engine performance really bad?

Thanks for the quick reply! Scorching or cracks, huh? I haven't checked that myself. Where exactly would I look for those? And how does the manifold sensor tie into all this? Is it easy to see?

Ok, so, on my Opel, it was pretty obvious once I located the intake manifold – look for the big plastic or metal thing bolted to the engine where the air goes in. The scorching was near where the manifold connects to the engine block. As for the manifold sensor, a leak messes with the vacuum, which throws off the sensor readings, causing engine misfire. I'd honestly recommend taking it to a workshop. It sounds pretty serious.

Thanks, that's really helpful. I'll have a proper look, but probably best to get it to the workshop. I'll mention the scorching and manifold sensor. It turns out the intake manifold was indeed leaking due to scorching. They're replacing it, cost me about 1180€. Hopefully, that sorts it!