The "Engine System Service Required" message has come on in a 2005 , five cylinder turbo S80 with 130K miles on it and idling is rough. What is odd is that when a mechanical gauge is hooked up to the fuel rail, it reads forty pounds psi which is good while at the exact same moment , on an OBD II computer hooked up, it reads 58 psi and rising. The fuel pressure sensor with 15,000 miles on it was replaced with a new one and there was no change in the reading ! What is up with this? Is there a software problem ? Is the fuel pump lying to the computer? The fuel gauge is very inaccurate too and that was not changed with a new fuel level sending unit. It seems unrelated as it has been inaccurate for along time .