Car runs too cool/intermittant autocheck annoyances

[Phil Rose]

At 1:55 PM -0700 10/22/05, Aaron Rosenstein wrote:
>
>After a 5 year break from Audis, I got the bug again and picked up a
>nice 91 200tq from a local seller. The car is in amazing shape overall,
>and has less miles than my last one, but still ahas a couple quirks.
>
>I'm concerned that the engine seems to runn so cool. Unless I'm driving
>around town slowly, the temp needle never get off the bottom three
>lines, and my last car always ran just under half even on teh freeway.
>
>At the same time, I get the annoying intermittant overheat/water symbol
>on the autocheck box,

Glad to hear people are still buying these cars! ;-)

Don't disconnect autocheck (especially when you might have a temp 
gauge that's not working properly), but instead find and fix the 
source(s) of the problems.

A defective MFTS (multifunction temp sensor) can cause both the low 
temperature reading _and_ the gratuitous warning for low-coolant 
level. If a bad MFTS is the source of the problem, the chances are 
that the A/C compressor won't work and that the max boost is low 
(e.g., 1.4 bar). Anyway, to test the MFTS, pull the connector off 
(i.e., disconnect)  the sensor: if that's been your problem, then the 
low-coolant warnings will stop (for sure), the maximum boost pressure 
may increase (assuming there're no other problems) and the A/C might 
work (if refrigerant pressure is OK). Of course the temp gauge will 
be dead. Simple matter to then replace MFTS.

The brake pad warning goes off when there's an _open_ sensor circuit. 
Fixing the brake pad warning is often just a matter of properly 
shorting the sensor connector wires (if the sensor circuit been 
defeated by a PO), or correcting a poor contact in one or both of the 
connectors (if you actually are using pads with sensor connections).

Oil gauge warning could require oil pressure sensor replacement as 
mentioned by Chuck.

Phil
-- 

Phil Rose				Rochester, NY USA
'91 200q	(153K, Lago blue)
'91 200q   (64K, Tornado red)			mailto:pjrose at frontiernet.net