1kd-ftv engine sound

[Waterfalls]

My Toyota 1kd ftv turbo 3.0D 2007 engine gives out a disturbing rattling knocking sound when in fifth gear above 100km/hr (approx. 2000revs/min plus) only when I step on the accelerator slightly, i.e. light load. When I depress the accelerator further, the rattling sound goes away, but the engine sound is a bit heavier than it was before this started.

Could this be a software of hardware problem? I am thought its a sensor problem, so I did diagnosis and no codes came up. From my little knowledge, it sounds like the injection timing is momentarily advanced, with a light load, to give that diesel knock when the timing is too advanced. Not sure though. I want to have an insight before I take it for checking.

[Bazooka]

How many kilometers on the engine? Does the engine have this rattle when first started from cold? Does it blow any smoke? The injectors are a common problem on these engines and do wear out. I'm not saying they are the problem in your case but are the most common cause of a rattle or knocking sound.
Give Baileys Diesel a call and discuss with them. They are exceptional when it comes to these engines.