[s-cars] irregular temp guage readings

Tom Green trgreen at comcast.net
Mon Jan 30 21:54:32 EST 2006

Thats good, Matt.  The channel 51 readout is from the sensor feeding  
your ECS,
so it is getting the correct information.  The heat on your feet  
doesn't plummet when
the gage goes down does it ?   That sensor is the MFTS  and  is the  
large brown sensor
located under the intake manifold and below the coolant pipe.  You  
can get to it.  It may
have a large rubber boot protecting it.  Just don't break anything  
else getting it out and
have the new one ready so the coolant doesn't keep running out.    
There has been discussion
about what size wrench it takes.  It's big, maybe 32-36 mm, but I had  
no problem getting an
adjustable wrench on it.

AutohausAZ.com had the best price I have seen recently.  YMMV

The sensor for the CH 51 engine temp is on the back of the block.


> Date: Mon, 30 Jan 2006 16:29:02 -0700
> From: Matthew Russell <skippertgore at msn.com>
> Subject: [s-cars] irregular temp gauge readings
> To: audi list <s-car-list at audifans.com>
> Message-ID: <BAY101-DAV8F001BCF0D7DFBE7D5005C8090 at phx.gbl>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
> Have replaced thermostat twice now, boiled both thermostats and both
> appear good. (opening around 87 C).
> HVAC channel 51 reads correctly (86-89 at operating temperature) -
> meaning the MFTS is functioning, correct?
> Symptoms are that temp gauge will start to rise as car warms up from
> cold, then will plummet down to almost nothing, then may come back up
> in 5 minutes or so (time varies).
> Is the sending unit for the temp gauge located between the back of the
> engine and the firewall, in a plastic fitting with coolant hoses on
> either end of the fitting, held in by a clip?  Is this the likely
> culprit? Can someone point me in the right direction?
> TIA,
> -Matt, CO
> 92 s4

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