engin low pressure

If you are refering to oil pressure, first check to make sure it really is a problem. Rent a mechanical oil gauge from a parts store and check it that way. It just screws into where the oil sending unit is located. The only thing that may be wrong is the sending unit which is a cheap, easy part to replace. If it still is low, then you need to remove the oil pan and check the oil pump and pick up screen to identify where the problem is coming from.