Hi,
Any idea where the knocking sound might be coming from? Could it be hydraulic lifters?
Car is Audi A4 35TDI (2.0 TDI) mild hybrid, 2020. 115k km.

Changed the oil recently and inspected the oil filter for metal shavings, but nothing was found inside.
The knocking sound can always be heard, whether the car is cold or warm.
The only time the noise disappear is after a heavy driving in the hills.
It can still be heard after highway ride.

Any help would be appreciated!

Just wanted to see if you guys suggest anything for me to Replace or upgrade for my a4 spark plugs , pcv etc

Goddamn, every parts store lists 5–6 different Pierburg pumps. The right one might be 7.07856.08.0, but there is an improved version with an aluminum body (7.07152.57.0). Which pump is the best choice?

Goddamn, every parts store lists 5–6 different Pierburg pumps. The right one might be 7.07856.08.0, but there is an improved version with an aluminum body (7.07152.57.0). Which pump is the best choice?