Same here, but I finally manage to fix mine...finally... It was going in limp mode due to a defective pre-supply pump, it was on her way out and didn't manage to keep up the 4 bar pressure when needed under load...very frustrating and hard to diagnose as the pump was buzzing when turning the key at start-up (normal buzzing sound nothing unusual) > the low rail fuel pressure errors pop up due to multiple factors: rail sensors, HP sensor, clogged/bad fuel filter, pre-supply pump (under car), pick-up pump (in tank), leaky injector or worst case, HP pump...
Exchanged mine with OEM SH pre-supply pump and the problem it is now gone , too bad it failed and left me in the middle of the road, forced to call a friend and tow it home.

Sorry to hear that you're still struggling with yours... you can try testing/clean solenoid (vacuum) valves and check vacuum connections if turbo actuator it's vacuum controlled. If it's electronic like mine, again hard to diagnose as electronic parts are prone to play@. Don't think the variable geometry goes so easy on these models....so I still think that there's a simple electronic/vacuum leak issue on yous when tubo cuts out....

 

Still not fixed, a lot better than it was but still going into limp mode and now having a problem with the turbo cutting out... one thing after another with this car.

 

Thanks and hope you fixed the DDE/limp mode issue. Update on mine: DDE still comes on...so I'm hopping to fix mine by replacing the high pressure pump sensor... By chance, did you get rid of the DDE/limp mode on high revs by replacing the MAP sensor?

 

Hi thanks for the update, I have done everything you done and seemed to help quite a bit but still went into limp mode with dde light at high revs. I have now just replaced the map sensor again as the last one I replaced it with wasn’t brand new and it hasn’t gone in limp mode since. Still does feel slightly down in power though, sometimes it feels way quicker than what it does other times so I’m jus trying to work out what the cause for this is now

 

Sorry for the late reply, didn't went in limp mode after cleaning the sensor located on HPFP, it happened twice in the past month at random occasions while pulling. I still bet my money on the HPFP sensor on mine....but overall it's good now... let me know if you manage to fix yours.

 

Hi, is yours sorted now then? Haven’t done anything to mine in the past couple weeks but looking to get all the parts I will need so if yours is now sorted it could put me in the right direction, thanks

 

Hi Alex, the car was with the mechanic last week. I left the old fuel filter in place, car didn't went in limp mode for past few days (assuming air locked in rail after filter change). I've blanked the swirl flaps, gave the inlet a good clean and replaced glow plugs controller along with one plug. Agree with you, glow plugs module fault isn't related to our problem and only comes in handy when temp is below 0. Decided to replace the module and plug as it's getting really cold where I live during winter (@ -25 C) and was running lumpy in the morning for a few seconds (first start and temperature was @ 2 degrees outside, not even below 0). Changed both thermostats and coolant as the main one was giving signs of failure (temperature drops while cruising or going downhill). While changing these parts, I've checked vacuum pipes and while doing that, we unplugged the HPFP sensor/fuel regulator - there was diesel fuel inside this plug, assuming the sensor will fail at some point but decided to clean the plug/connector with contact spray till then, apparently this sensor generated the low rail pressure fault on my car at random occasions, depending on load. The other 2 sensors on rail look fine and wiring/connections are ok. Another suggestion is to check this sensor located on HPFP, on other forums I've read that it's prone to fail, similar to rail ones. Easy job, visible from right side below the EGR valve. If you have INPA you can do a live reading on injectors this will give you a starting point or idea if they are at fault or leaking too much. Hope you get it fixed soon!

 

Hi thanks for the reply, mine also has a fault code for all 4 glow plugs and glow plug module but didn’t think to add that as didn’t think it’d have anything to do with it but mine also starts perfectly fine, maybe I’ll look into changing the module for the glow plugs next and if that doesn’t do anything I’ll do a leak test. I’ll keep you updated anyway, thanks

 

Thanks for the update ... Mine started developing the above symptoms (low rail pressure errors) after changing the fuel filter (brand new). I'm going to change again the filter next week (will try different brand, I'll probably go with OEM this time). Checked the rail sensors plugs and wires including injector ones-nothing). Mechanic said that it could be dirt inside rail filters, probably picked up during filter change...gonna check that as we're going to remove the inlet to blank swirl flaps and replace gaskets.
ECU stores 3 rail low pressure and all 4 glow plugs errors (assuming it's the relay at fault for all 4 glow plugs errors and should only affect start-up) doesn't cut off, starts fine, it runs fine but if I floor it, it goes into limp mode... I can suggest a leak test on injectors as you already changed rail sensors and pumps... hope for the best...I'll keep you posted.

 

Nope still not fixed, sorted the issue of it not starting by changing the fuel pump under the rear seats and changing the inline one, definitely runs better but still getting dde light and limp mode! No idea where to go from here though

 

Hey Alex!

Did you get it fixed eventually? Mine does the exact same thing.