I seem to be having a problem just recently with my oil pressure. My car starts up fine and runs great. However sometimes when I come to a stop and the rpms let off my check engine light comes on. I look and see my oil pressure gauge says the pressure is at zero. I just rev the engine and the gauge gets off zero and goes back to normal. It doesn't matter whether the car is in drive or not. I think it might be the sending unit for the oil pressure, but i wanted some help and opinions on this? If it is this does anyone know how much it costs and how easy it is to replace? Thanks for the help.