ThirdEye

My engine temperature gauge has progressively began to report lower and lower temperatures. Now no matter whether around town or on the freeway it, once warmed up it is only half way between the middle and C(bottom). I also noticed that it takes a lot longer for it to reach this temperature compared to my dad's 03 1.8t Passat. Is this more likely to be the thermostat, or just a bad coolant temp sensor? If it is the thermostat I know it is stuck open, but is there any way to check? I happen to have an extra thermostat that came with my timing belt kit that I never replaced, however I would prefer not to have to flush the coolant again as it is kind of a PITA. Also, would either of these throw codes I could check on the vag com?

TIA

ModifiedA4

<center><img src="http://pictureposter.audiworld.com/143/bad-temp-sensor.jpg"></center><p>this is a pic of my dash with a bad coolant temp sensor. the oil temp is normal, but the temp guage would bounce around while i was driving.

a bad sensor will throw codes.

CrazyINP-12V Ivan

w/o changing one and after that another is to get temp. meter, warm up the car and open very carefully the coolant reservoar, measure the temp and check if is the same as the VAG report.

ThirdEye

The oil temp also has seemed lower than it used to be, what is optimal oil temp?

SilverA4Fun

If you dash looks like Modified's then it your coolant sensor. Quick fix in the tech section.

SilverA4Fun

200ish, unless it hot out or you've been running your car hard then it will be higher

ModifiedA4

if you live in the north-east (very cold recently) you car wouldnt warm up if you had a stuck open thermostat.

with a broken coolant temp sensor, i could make the needle bounce around if i did third gear wot runs. also, your mpg will get ****ty.

QuiksilverS4

My coolant sensor is on the fritz too. WOT 3rd gear makes the temp gauge dance.

ModifiedA4

yup...those are the symptoms.