[s-cars] Fluctuating Temp Gauge

[Dave Forgie]

Iain:  You can check the temp gauge reading against the temp reading
from the climate control head Channel 51 (with the heater on) as per:

http://forums.audiworld.com/s4s6/msgs/136636.phtml

If the CC reading is low and your temp gauge is low, the thermostat has
failed open.  If the CC reading is high and the gauge is low, then your
multifunction temp switch on the coolant manifold under the intake
manifold has failed (see ETKA sketch and part no. at):

http://forums.audiworld.com/s4s6/msgs/136602.phtml

To replace the MFTS, you need a deep 29 mm socket and a stubby rachet.
Takes 5 to 10 min (on a cold engine).  No need to drain the coolant down
(on a cold engine). You can do the Dutchboy in the dike thing with one
finger after the dead switch is removed. Feed the new switch to the dike
hand and start the threads by hand. You might lose 250 mL.

HTH

Dave F.