Nissan Maxima: Is my knock sensor dead from these readings? 97 Maxima Nissan

I've been plague by a "knock sensor" check engine light that won't
go away. I check the knock sensor while still bolted to the engine
block and got these readings at 2K-rpm:

DMM: ~20mV AC, 5.5M-Ohm.
Scope: ~20mV or ~ 30mV peak-to-peak when back-probe connector.
ECU to sensor supply power ~ 5VDC, when connected ~ 3.8VDC.

I remove the sensor from the engine block to test bench and
vibrate it to achieve this readings:

DMM: 76mV AC, 576K-Ohm.
Scope: 76mV peak-to-peak .

I reinstall the sensor into the vehicle and reset the ECU and no
improvements. Normal torque is about 50-lb? Has the sensor gone
bad/aged or the data retrieval technique is flawed?

Thanks

> "Tibur Waltson" <com> wrote 
 

Thanks all. There was an O2 problem also.

All solved. Here's a KS comparison.

New knock sensor:
0.003 VAC with light tap using DMM
0.001 VAC w/ no tap
Resistance = 0.54 M-Ohm
Scope = Smooth curve AC sinewave

Old knock sensor:
0.033 VAC with light tap
0.001 VAC w/ no tap
Resistance = 5.49 M-Ohm
Scope = appears to be an AC sawhorse

Estimated torque on identical Bosch Japan sensor to
block = 15ft-lb. Bought from europartsdirect.com.

Tibur Waltson