FreelanderMarto my experience with failing glow plugs does give the symptoms you describe. My old TD4 was terrible cold starting until I changed the glow plugs. Failing battery (or low charge) tends to throw a terrain response error-the error message usually comes up with terrain response disabled. My SD4 is slightly different in that it fires up almost immediately but is momentarily lumpy. Unfortunately failing glow plugs don’t throw up an error-just a symptom of poor starting in low temperatures. I can understand the amusement from our Scandinavian cousins, -5c must seem a little tame if not balmy for you guys😀

Put a new battery on it anyway was even after a long run the battery only showed 11.7v . But still the lumpy start every now and then. Just been out to start it today and a lumpy start and will hardly Rev up so turned it off and turned ignition on and off 3 times then started the car took longer to start again but ran more smoothly. How hard is it to change glow plugs and what is a good brand. Ta GS Sd4 2012

See here for an excellent write-up on changing plugs.
https://www.freel2.com/forum/topic11567-45.html
I used NGK plugs. Make sure you get right type for your year. 11v for early ones, 5v for later. Andy
Freelander2 HSE (59 Plate, MY10 spec)