Assuming you have an oil pressure gauge:
If your engine has low oil pressure, it may be because the oil pump isn't working. To check if your oil pump is working, do the following:
1. Remove the oil dipstick and start the engine. The needle on the pressure gauge should rise to indicate that there's enough oil pressure. If it doesn't, then there may be a problem with your oil pump.
2. With the engine still running, turn off the ignition and remove the key. This will allow you to check if there's any leakage from the valve cover gasket or elsewhere. If there is, then it's likely that your oil pump isn't working properly.