b6 glow plug light flashes and engine fault help

[stuburg]

Hi , went to start the car the other day 2.0 tdi 140 and the glow plugs lights started flashing and then the warning engine fault see garage came up in the window, I took the key out and tried again and it was fine, it's done it a couple of times but only when cold not if its warmed up.

I took it and had the codes read the other day and they said theres 2 canbus wires and only one of yours is connected and that there was an open connection somewhere, they found something had come loose in the engine bay and pushed it back in. they said that it was because of that but I don't think they scanned it again.

anyway as you probably guessed it happened again today so any ideas what it could be.

Im takin the car in to have the stat changed on saturday so will get them to have a look at it again but would be good if I had some ideas what it might be.

thanks in advance for any help Stu