Audi 100 quattro temp gauge probs

UK Audi 100 2.3 1992 avant temperature gauge works when it feels like it but
on test
deflects fully if shorted and warning buzzer works for over temp and
autocheck shows temp problem so replaced "large"4 pin sensor on top of pipe
to right of block with new 3 pin from euro car parts £25 (Audi replacement
now has 3 pins £75 !!) !! everything worked fine now two weeks later back to
same situation gauge fails to work but tests out correct full deflection etc
conned Audi dealer into checking their techie said sensor was ok don't want
to keep spending £25 for 2 weeks of temp gauge working. there is another
small temp I think sensor under the same pipe directly below the one I
replaced does this have any affect on temperature gauge what does it do?
? Has anyone used a sensor from another vehicle to do the same job any
advice gratefully received

Paul,
Maybe a broken wire or shorting in the connector? If it's the ol'
Multi("mal")function temperature sensor like the one on my '87, the rubber
boot over the connector has a tendency to collect coolant/water and short
out the sensor connections.
Cheers!
Steve Sears
1987 Audi 5kTQ - rubber boot sealed with a hose clamp
1980 Audi 5k
1962 and '64 Auto Union DKW Junior deLuxes
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"Paul Wickham" > wrote in message
news:yxpuc.352$t91.311@newsfe2-win...
> UK Audi 100 2.3 1992 avant temperature gauge works when it feels like it
but
> on test
> deflects fully if shorted and warning buzzer works for over temp and
> autocheck shows temp problem so replaced "large"4 pin sensor on top of
pipe
> to right of block with new 3 pin from euro car parts £25 (Audi replacement
> now has 3 pins £75 !!) !! everything worked fine now two weeks later back
to
> same situation gauge fails to work but tests out correct full deflection
etc
> conned Audi dealer into checking their techie said sensor was ok don't
want
> to keep spending £25 for 2 weeks of temp gauge working. there is another
> small temp I think sensor under the same pipe directly below the one I
> replaced does this have any affect on temperature gauge what does it do?
> ? Has anyone used a sensor from another vehicle to do the same job any
> advice gratefully received
>
>