Have the 'Service Soon' message popping up intermittent on my Astra J 2001 2.0 Diesel, and the fault codes read are:

P0087 - Fuel Rail - Too Low Pressure - Unrecognised State
P0399 - Cylinder 1 Pressure Sensor Circuit - Malfunction - Faulty Function

The car  seems to drive OK, no general loss in power but am noticing when changing gears the engine revs seem to overun if the gas is less off when the clutch is down.  i.e. if chaning at 3,000 rev, and i put the clutch down and let off the ga