2006 Citroen C5 2.0 HDI; need help with some error codes (P1693,U1118,U2001)

[Victor497]

Hello everybody, i have a 2006 Citroen C5 2.0 HDI and have been dealing with some error codes for a bit, it all started when the "Depollution system faulty",appeared and went straight into limp mode. I scanned it for errors and showed "P0088 Fuel rail/system pressure too high", dropped it off to have it fixed. The fuel rail pressure regulator and the fuel flow regulator(i think it's called?) were changed, the error still persisted. The mechanic found some wiring issues which were fixed, and now i'm confronted with the following situation: It starts perfectly, but after a few minutes of idiling, the same error appears P0088, the engine changes its sound, hooked up a scan tool, and noticed that the values for rail pressure are as following: when the depollution system error isn't present the fuel pressure reference at idle is 250.85bar, and actual fuel pressure 250.85bar. When the depollution system faulty appears the values change to: fuel pressure reference at idle 344.xx bar and actual fuel pressure fluctuates between 500 and 700 bar at idle. Also after that happens the following error codes appear as well: "P1693 Remotely Controlled ECU Wake-up Start/Stop Function Reception Error", "U2001 Remote Controlled ECU Wake-Up: Main Wake-up Request Absent Or Invalid", "U1118 [SID804] BSI ECU Reception Value Recieved Incorrect [SID802 BSI ECU Reception BSI or Air Conditioning". Anyone ever encountered this or have any idea what's going on? Thank you for the replies!

[PaulC5]

Possibly the fuel pressure sensor has a fault.