Re: coolant temp sensor

["Fred Munro" <munrof@isys.ca>]

-----Original Message-----
From: Phil Rose <pjrose@servtech.com>
To: quattro@coimbra.ans.net <quattro@coimbra.ans.net>
Date: Wednesday, June 17, 1998 2:30 PM
Subject: coolant temp sensor


>The ACC diagnostic channel 01 ('89 100) has always produced an 09 code,
>which I have ignored until recently. According to the Bentley, the 09 code
>means a faulty "engine coolant sensor"--the one that's inserted just upside
>the large coolant hose/thermostat flange. I ran the electrical tests and
>everything appears as per specs--both the sensor resistances and the
>voltages at the connector pins. So...why does the ACC tell me there's a
>problem here?
>
>According to the manual, the symptom of a defective coolant sensor will be
>hard cold-starts and rough running during warmup. I've never noted the
>former, but the latter symptom is sometimes present in winter. Is it
>possible that the 09 code from ACC channel 1 of '89s is not meaningful?
>
>Phil
>
>Phil Rose Rochester, NY



Hi Phil;

    You may have a bad connection which the A/C control head interprets as a
defective coolant sensor. I just had a problem with the A/C head setting 07
and 15 trouble codes - defective temperature control flap motor and/or
feedback potentiometer. Also had physical evidence of a problem - the unit
wouldn't maintain temperature. I followed the Bentley troubleshooting
procedure and it identified the temp flap motor as defective. Hmmm, that
motor looks awful expensive. Put the magical Stabilant 22A on the A/C head
connector pins and the temp flap motor connector - problem solved! It now
works like a charm and no more trouble codes.

HTH

Fred Munro
'91 200q  254k km