Definition of discourse marker noun from the Oxford Advanced Learner's Dictionary
When an engine starts knocking, one of the first things a mechanic will check is the oil pressure. A warning light may come on in the car, and adding sufficient oil will solve the problem. Sometimes, a knocking noise is caused by loose torque converter bolts or a loose flywheel.
This is proven by the part that is called as the knock sensor. It is connected to your vehicle's computer system in order to determine and serve as a warning signal against engine knocks. This occurs when the spark plug fails to trigger the fuel operations properly. As a result, your engine cannot run smoothly.