Check Engine light on '90 200 Q

[ozitzmann@atmi.com]

My Check Engine light comes on above 3000 RPM, but only on very light load
(slight acceleration or constant speed).  It's never on at more than 1/2
throttle.  I have the 2144 fault code (knock sensor #2), but I don't want to
spend $130 if the problem is in the wiring or elsewhere.  Is there a way to test
the knock sensor?  BTW, I have checked the archives and not found an answer.

Thanks in advance,
oz