CEL on for coolant problems

Good morning everyone. I’m new here. I have a question about the coolant system on a ‘06 Beetle TDI. The code read coolant not heating up. Guessing it’s a thermostat or a sensor so I was gonna replace them both. My question is the part the sensor is mounted two has three other parts screwed into the top. What are they for? They look similar to glow plugs.

They are glow plugs, to try and help get heat into the heater core in the cold mornings. Only on manuals transmissions.

Change your thermostat and coolant sensor (on the back of that flange) and you'll be good for many miles. The sensor is known to go bad, they are cheap, you can try replacing it before the thermostat, but the t-stat may have actually failed as well.

My wife's '07 gas NB would illuminate the overheating light when started in very cold weather. The solution was to clean the temp sensor with an old toothbrush.

On a cold engine open the coolant reservoir cap and look inside- you should see two metal probes pointing down into coolant. Brush vigorously as best you can. For us it was problem solved.

Hope this helps, John