DI2 Crash Protection query

I've got an XTdi2 rear derailleur on my Merida E160 which I've had for over 3 years now. Unfortunately the RD failed about 6 months ago and the only option was to replace it with a new one (seemed to be an electrical failure - Shimano couldn't offer e repair)

The old RD never once went into Crash Protection Mode, but the new one has done it 3 or 4 times now. I'm riding the same trails, with the same percentage of good and bad line choices, and I haven't actually crashed to cause it to go into CP mode - it just does it on it's own accord. The trails I ride are pretty rocky and steep, so I'm assuming it's just being bounced around violently enough for it to think it's been hit - but it seems strange that it never happened on the original one.

Does anyone know how the CP mode is activated, and is there any way of adjusting the sensitivity to stop it doing this so regularly? Or just turning it off?