Glow plug fault codes. Best clear the codes and see if they return. They might have been replaced already

 

Battery was disconnected yesterday for a short while as I am having a problem with the cd30 head unit so wouldn't that have cleared it

 

Nope. Needs code reader to clear it.

 

If it's running all right, and you don't have the warning light (car with spanner through it) lit, then as above, it's probably been fixed but the codes not cleared.

 

i have got the spanner light on

 

Then it needs to be investigated and fixed

 

Use a MM and test the resistance of each plug, one wire from the meter on the tip of the plug and the other to ground (Neg post on the battery will do) and post the result of each plug here or just replace any that have a resistance above about 3 ohm.