D5 Stumbling Idle on Cold Start

[agent006]

My 2013 XC70 D5 has a problem when starting from cold. This is only really evident at low temperatures below 10c.
The car starts fine and settles to idle for a few seconds but then the idle becomes lumpy, the revs drop briefly then it picks up again, settles down to idle before repeating. It's smooth if I pick the revs up with the accelerator.

No fault codes either on my OBD or on Vida when the specialist checked it a while back. Unfortunately it's never been cold enough for them to actually recreate the problem when it's with them so it's remained a mystery.
It's not a huge problem right now but I want to sort this before it becomes something worse.

Any ideas?

[Simmy]

check the glow plugs as a starting point.

[Kev0607]

-Glow plugs
-Dirty fuel filter
-Injectors

Fuel filter is the cheapest. Glow plugs are around £20 each roughly, but you have 5 of them. Chances are, if one is gone, the others won't be far behind or starting to wear. It makes sense, if budget allows, to replace all of the glow plugs in one go and be finished with it.

Test before you replace them though with a multimeter, as there's no point spending £100 for nothing. Sometimes, the glow plugs have to be completely knackered before it throws a fault code, but if they're wearing, it can cause a lumpy idle (just not bad enough to throw a code).