In normal operation, the engine oil is especially important for the smooth operation between the combustion chamber and the engine block. The pressure indicator shows how properly it is working. A sudden pressure may be the result of reducing viscosity of the engine oil, which may be caused by dilution with fuel (problems with an injector or small amount of oil), reduced oil content in the system (due to oil leakage, a large flow of oil or oil pump failure) or wear of mechanical components.