first you will need a 10mm spanner or deep socket, a 13mm socket and a t25 torx bit and can of intake/carb cleaner and most importantly some gloves my hands are still dirty and safety remove engine cover and locate egr valve at the top rear right hand corner of the engine joining onto the inlet manifold.
you can remove plug to solenoid now or when valve is off is a bit easier to get at it.
mine has a bracket fixed to it that requires removal first by undoing the two nuts with 10mm the two large bolts with 13mm socket were slackened off, then the remaining 4 bolts to the manifold were removed the 2 on the right were easy but the 2 on the left needed a spanner as my socket was not deep enough, there is a metal gasket between valve and inlet manifold dont lose remove the 2 large bolts but be aware there is a metal gasket below valve between flanges, i kept and reused both of my gaskets but next time its cleaned will try to get new gaskets.
this was carbon build up in intake side of valve i was supprised for only 16,000 miles.
this was exhaust inlet side of valve not clear in pic but was approx 2mm of build up all over.
this was build up in inside of the inlet manifold looked same at 2mm or so, i did not disturb any of this as didnt want chunks going through my engine.

next you will need to split the valve into two by removing the 4 screws with your t25.i scribed the join of the two halves to make sure it goes back together in same position.
there is nothing you can loose out of valve body so now get it a blast of carb cleaner, i recommend safety glasses as i got quite a lot of splashback i also used a small stiff brush to help clean(just dont use one that will lose its bristles in the valve)
this was intake side finished and clean you can just make out valve seat(being held open)

this was exhaust side with another valve seat(being held open)

the solenoid half of the valve required minimal cleaning as its only leakage through the valve stem that gets in there.check for free movement of plunger mine was nice and free, i thought about spray lube inside but decided against it incase it gunks up so left dry.
all thats left is to reassemble the two halves and then refit valve in reverse order be carefull with gaskets.
i decided not to clean the exhaust gas pipe, will leave that for next years clean but if you decide to do it it looked like a 5mm allen key is required to undo a clamp down below im guessing theres a gasket of some sort in there and would need realigning upon refitting.
not sure on correct diclaimer so follow this guide at your own risk.