Multi-Function Temperature Sensor (MFTS) Diagnostic

[Huw Powell]

On 11/25/2011 3:04 AM, Marc Boucher wrote:
> Could anyone recommend a diagnostic procedure on the Multi-Function Temperature Sensor (1990 Audi 100 NF engine)?
>
> My temperature gauge steadily rises as the car warms up but at some point it reverses, heads back to cold and stays there for 5-10 minutes.  At some point when the engine reaches operating temperature it once again rises until it hits the normal range, and then it usually (possibly always?)stays there for the duration of the drive.

Wild shot, but could be thermostat issue and the sensor/gauge are fine?

> I realize that the MFTS is a failure point, but its possible that its also the temperature gauge or the wiring.  Thus if there's a diagnostic that I can do before replacing it, I'd like to try.
>
> Should replacement be necessary, does it simply unscrew from the bottom of the coolant outlet, or is it necessary/easier to remove the coolant outlet first?

Yes, unplug, unscrew, replace, reconnect.

> Thanks,
> MC
> _______________________________________________
> quattro mailing list
> http://www.audifans.com/mailman/listinfo/quattro
> http://www.audifans.com/kb/List_information
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.1872 / Virus Database: 2092/4637 - Release Date: 11/24/11
>
>