Originally Posted By: Tornado Red
I had the notorious glow-plug fault on my '03 Golf TDI for about 6 or 7 years. A couple years ago I replaced the glow plugs, then the harness. For about two years, no CEL. And now it's back, for the same reason. So, for at least two-thirds of time since the car was new, the CEL has been on. The car runs great, so I don't worry about it.
I've thought about wrapping the four wires in the harness together, so the voltage or amperage or whatever is being measured will be identical for all of them.
My '03 Golf TDI had the harness and all four glow plugs replaced twice under the emissions warranty, all before 73k miles. It did not appear to be a cheap repair either, one of the warranty invoices they actually showed pricing instead of the N/C and if I remember correctly it was like a $900 job.