Nissan sentra gxe error code p0300

I have a 02 nissan sentra gxe. The service engine soon light came on a few days ago. I am also loosing coolant. I did a pressure test and there is no visible coolant leak. Looks like I need to replace the head gasket. Did anyone have this problem and did replacing the head gasket fix the issue ? It looks like quite an expensive fix.

sounds like head gasket. Look for milky color in oil, also there are ways to check for air bubbles in radiator which is a sign and possibly white smoke out the pipe. Gasket itself is not too expensive, it is the labor of like 6-7 hours due to getting to the cylinder.

You also need to do a compression test and look for 120 psi across the cylinders. If you show across 2 cylinders low pressure you can be sure of the head issue. Also do a leak down test if possible. All these will give you information on valves, rings and gasket.

If you are going to do a compression test, that means removing the spark plugs. Look at the plugs when you take them out. If one of them is shiny and clean, that’s a pretty good clue that you are leaking coolant into that cylinder.