2006 Diesel Hilux, EGR fault, error code (P0400).

Ah! Now I remember!
Customer reported Engine light on, and a P9400 error code (EGR not receiving expected exhaust flow).
This doesn't mean it's necessarily the EGR that's faulty. Rather, it could be a number of reasons that could cause this.
When I flattened the Accelerator, the Engine only revved to about 2 grand (probably in Limp Mode), but it smelled like it like it was running really rich.... choking, if you like.
I checked to see if the Turbo boost controller was moving, but there appeared to be no activity. so I carefully removed the top of the Electric motor, to check the brush condition, which appeared to be fine. I then wound the Armature (not the Stator, as I said in the video) all of the way, in both directions, to see if the gate was moving freely, then put it into the approximate centre position, before refitting the outer casing of the motor (retaining the wave washer with a Rare Earth Magnet on the outside), reconnected everything, cleared the codes, and kicked the Engine over. Now, the Engine revs cleanly and freely, with no Engine light coming on.
My guess is, the waste-gate was stuck, or there is resistance between the brushes and the Commutator, due to inactivity, when idling of long periods, as the Armature twitches back and forth when there is no demand for boost or waste.
Please feel free to put your two-bobs-worth, in.
Hope this helps.