I'll give you the long answer here. Our injectors are electric over hydraulic, meaning there is an electric solenoid on the top of each injector sitting there waiting to be fired by the PCM/IDM, the bottom half of the injector is filled with fuel and the top half is filled with oil, the HPOP supplies the oil. Each time the solenoid is fired the oil pushes down on a piston that pushes the fuel into the combustion chamber, the oil is exhausted out the top side of the injector for a return trip. The higher the pressure the oil is, the better atomization you get of the fuel. The PCM will set a check engine light IF the pressure of the oil is too low.
Thats a basic crash course on how our injectors operate, there are guys here that could make it alot more technical than that. I dont see in your signature line that you are running modified injectors? Or are you? Have you confirmed the P-1211 code yet? I dont see in this thread where you have. In any event, if you are still on the stock injectors you really shouldnt be setting the p-1211 unless you have a wore out HPOP or a malfunctioning IPR valve.
Do a couple things for me, confirm the P-1211 code, let us know what size injectors you are running, how many miles on the engine, how many miles since last oil change and what type of oil. Do you have a rough or uneven idle speed too?