1998 passat 1.9 tdi internal heating

[Brains188]

My temperature gauge (coolant water) usually reads about 75 deg. C (not sure what it should read, 90 degrees i assume, but barely ever moves above that). My question is, Could the fact that the temperature of the coolant staying low, have any bearing on the "in car" heater, which never really goes above luke warm?
Hope this post is in the correct section.

[zollaf]

well, the heater uses the heat from the engine, so a cold engine results in a cold heater and is a sure sign that you require a new thermostat.

[Brains188]

Thanks for the reply Zollaf, looked in the haynes manual and it unfortunately poised another question, is the Temperature gauge on the dashboard controlled by the thermostat or by a coolant temperature sensor? or are they both the same animal?

[zollaf]

the coolant temp sensor sends a signal to the gauge, so yes the cts does control what the gauge reads, but because your heater is cold it means you need a new stat. disregard what you have read in the haynes manual and fit a new stat. its opening early and your coolant is not getting upto temp. you will also get more mpg as well, after you have fitted a new stat. get a proper make, febi or gates or genuine, not some cheap piece of ebay.