How "fail safe" is the knock sensor? Could it leave detonations unsignaled to ECM?
I took a 20min test drive with a logger hooked up because I noticed weird clicking noise coming from engine. Frequency of clicking follows motor rev.

(It's my first CAR and I've had it only about 2 months, so I don't recognise all the sounds this thing makes)


In the end of drive, logger software had counted only 6 knocks.
(I've heard 6 counts is acceptable, please correct if I'm wrong!)

Could this noise be pinging?
Or could EGR make this clicking sound. (I tried locate source of the noise, it sound like it's coming under the plenum) So my guess is the EGR.

Thanks for any advice!