It is a 2006 Mini Cooper S R53. The error code is p0326.

What is the error code number?

Also, year & model of your MINI.

i cant help much from a distance! but if a knocking noise appears in the engine, no matter what the source! and the frequency is such, then it could trigger the sensor. Try locating that knocking as you plan!

My car has 68k miles on it. It had a front end collision and was salvaged. I had to take everything off the front in order to repair it. (This is when I bought the car, after the impact) Then when I started driving it and the knock sensor came on. Cleared the code, and it came back almost right away. I have cleared it probably 5 times. I have done quite a little bit of research on the knock sensor problem and I have tried what seems to be about everything. 

What I've done:
1) Replaced knock sensor
2) Tried Octane 104 Booster
3) Tried a bottle of seafoam engine treatment
4) Replaced spark plugs (NGK IRIDIUM)
5) Replaced Ignition coil (MSD)
6) Replaced Ignition wires (MSD)
7) Tried gas from other stations
8) Tried following the wire back into the engine (it doesn't appear to be severed from the front impact)

I have been listening closely to my engine, and there appears to be a slight clicking not anywhere near as extreme as the"DEATH RATTLE" but still audible. I am going to try replacing my timing chain tensioner this week and I am also going to try replacing my throttle body and see if that somehow is causing the problem.

So I was wondering if anyone else has had this mind boggling issue and if they could please help me!
Thanks