Knock sensor signal high code - Mini John Cooper Works

Hi, 

New user here.

I recently bought a 2010 mini john cooper works as a non-runner, I stripped the engine down and found a blown piston. I've done a complete engine rebuild replacing parts where necessary and the engine runs really nicely. It sailed through emission tests and drives well. However when driving up hill at ~60-70mph under constant load it keeps going into limp home mode with a p0328 code for knock sensor circuit high. The mini specific code is 2D9B.

I've been through a fairly significant and expensive part changing process (including new knock sensor, ECU sent away for repair) and haven't got anywhere, that's when I started learning a about more detailed diagnostics and I've now watched loads of Scanner Danner videos on youtube. It's led me to investigating the voltages going to the knock sensor and I think I'm on to something but really need a bit more help on my next steps.

With ignition on I read 1.6V DC at both signal and ground cables. This is measured with a wire piercing probe at the ECU multiplug. When I unplug the knock sensor from the other end of the harness these voltages remain at 1.6V DC. The ECU has already been away to a reputable ecu repair company who can fully test this make and model of ECU and they confirm no issues with the ECU.

I'm convinced from everything I read that I should most likely have 5V on the signal and 0V on the ground with sensor unplugged, with sensor plugged in I should have 2.5V drop across the sensor. There's no way I should have the same voltage on both signal and ground?

With ignition on, voltage between knock sensor signal and knock sensor ground is 0V, resistance is ~64kOhms.

Question is, if the ECU is confirmed to be good, what could cause incorrect voltage at ECU output on the knock sensor cables?

Thanks for any help you can give.
Ben
 

I've had confirmation from the ECU repair company that they checked all voltages at the ECU and everything reads OK. They also tested the ECU under load and all is OK.

Does anybody know if other sensors could be running on the same supply as the knock sensor and affecting it's output?