add blue

Hi all,
I have a 2008 1.6 HDI with 38,000 mils on the clock, We were going to visit friends over the week end some 600 miles round trip so just up the road from us we filled up with diesel but about 5 minutes later the aura light started to flashing and a warning light came on center display saying 700 mile before the engine will not start. we stopped checked the fuel cap and tried to restart but still the same. we continued on our trip and when at our friends i put 9 Ltrs of add blue in the tank checked and it has the modified cap with vent and it is not clogged up. but still the same we are now home with 100 mile left displaying before the engine will start, I am also told there is another additive tank under the car that could cause this problem but not sure so just wondering if anyone has had the problem or knows much about it. I have also been told by a friend it could need a new tank at £1800 plus fitting but not sure it they really know much about it.

 

Sorry I have an update that may help, So a couple of days before the trip the engine management light come on and I put the code reader on the car and it said 'P2207 NOX SENSOR HEATER CONTROL CIRCUIT HIGH BANK' I reset it and it went off for a while but the next day going over a bump in the road it came back on so I assumed bad connection. On the start of out journey the week end it came on again and I tried to reset it but it came straight back on. When at out friends before starting to come home I tried to reset it and it went off and has stayed off for the 300 mile journey but I have just read on a google post where some one said they had the same problem with there 2008 Aura light on miles counting down before it wouldn't start and it was the NOX sensor so just wondering if this makes sense to anyone and if I should start with changing the NOX sensor?