Hmmm. Reading this thread with some interest. As far as I can tell I don't have a 'real' glow plug issue BUT have had vag-com faults that suggest glowplug issues with wiring faults to glowplugs 2 and 3 - it's a very long story, and is well detailed by Fester and I in the LCR twin fans thread around page 7.
When the warning light first came on the VAG specialist I went to said they wouldn't touch glowplugs because they were "tricky to do" and they'd have to refer me to "an engine specialist" for "a days work" to get them replaced. Smelled more than a little fishy at the time, and having read this thread I'm wondering were they attempting to fob me off?
Interesting that the wiring loom for glowplugs is under the battery compartment... as that's where the fans issue fix unit goes that's thought to be interfering and causing intermittent glowplug warning lights for Fester and I currently.
The routing of the wiring under the battery has nothing to do with the fan problem. I have just replaced the loom for the glow plugs as I had the wiring fault code to plugs 2 and 3. The fault has gone now so I am confident I have sorted my problem. Care is needed when replacing the plugs although its easy to do. It is however easy to cross thread the cylinder head with the new plug if the angle of fitment is incorrect. If anybody reuires a step by step guide to replacing the loom let me know!
Glynn