Mercedes E Klasse Diesel Low Oil Pressure and Mechanical Noises

Good heavens, that doesn't sound promising! A low oil pressure warning coupled with mechanical noises is definitely a cause for concern. I must ask, did you ensure the correct engine oil type and viscosity were used during your recent oil change? Did you verify the engine oil level after the change? It is also worth pondering if the oil pressure gauge is functioning correctly. While an oil pressure sensor fault could trigger the warning light, the noises suggest a more serious, underlying problem. Does the oil pressure warning appear immediately after starting the engine or only after it's been running for a while?

I used the oil type specified in the manual and the level is correct. The warning appears after the engine has been running for a few minutes. Is it likely the oil pump then?

Given that the correct oil was used, the level is verified, and the warning appears after a delay, a defective oil pump does become a strong suspect. The noises you are hearing are likely due to insufficient lubrication reaching critical engine components. While I cannot definitively diagnose the issue remotely, continuing to run the engine in this condition risks causing significant and potentially irreparable damage. My strongest advice would be to cease operation immediately and have the vehicle inspected by a qualified mechanic. Do you concur that professional assessment is now warranted, given the severity of the symptoms?

Thanks for the advice. I took it to a workshop. It was indeed the oil pump. Repair cost 755€ including parts and labor.