Q: Low oil pressure light stop engine

This light will usually come on when one of two things are happening. Either the motor is in fact low on oil or the oil pressure sending unit is not working properly and may be producing a faulty reading. In your case, it sounds like your engine may be dangerously low on oil if there is a knocking sound coming from the engine area when this light is on. When this happens due to a lack of proper oil pressure, the result is usually damaged bearings and other internal engine components that often times require the engine to be rebuilt. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to determine what may be causing your low oil pressure light to come on.