Re: Testing Knock Sensors

[Tony Lum <tlum@flash.net>]

At 11:06 AM 12/2/99 -0500, you wrote:


>Is there any way to test a knock sensor?  I have a 2144 fault code, but I want
>to confirm that the sensor is bad before I replace it (expensive).
>
>Thanks,
>oz
>
>'90 200Q Avant
>

Hi oz,

The knock sensor is really a piezo (crystal) microphone.  I think the only 
way to test it would be with an oscilloscope.  Connect the leads, lay it on 
a metal surface, then tap it with small tack hammer.  If the display 
doesn't spike, you need a new sensor.

Regards,

--
Tony
_______________________________________________________________________

Tony Lum                                  1987 5000CS Turbo Quattro
Berkeley, California, U.S.A.                1985 4000CS Quattro
Audi Owner/Driver/Mechanic by Necessity ;^)   1980 5000S Sedan
QCUSA Member #6885                             1987.5 Coupe GT
_______________________________________________________________________