I got in my car yesterday to head to Jason’s place, and noticed that the Check Engine light was on. I didn’t think much of it, as it was probably just my seasonal “Replace a glow plug” reminder. When I got home, I scanned it out with VCDS, and discovered two codes:
P0671 (Glow plug #1, ie Cylinder #4, driver-most end)
P3105 - Valve for Intake Manifold Flap (N239): Open or Short to Ground
I’d never seen the P3105 before, but it didn’t sound good. I did a bit of googling, and came up with this post on TDI Club. As you can see, mine was a bit more than a frayed wire; I would have used the usual (and VW-endorsed) crimp repair, but I was all out of splices, so I sucked it up and soldered it.
Further, because the purple wire was already disconnected, I covered the length of it in heatshrink tubing. I then wrapped the yellow wire in high-quality 3M electrical tape, before wrapping both wires together, and reinstalling the split-loom tubing.
One thing the linked post wasn’t super-clear on was the exact location of this wire. It’s the cable that plugs into the sensor behind the intake manifold.
Once that was done, replacing the glow plug was a minor matter. Total time, according to the Garage Cam was 40 minutes, including reassembly and cleanup.