Hi these are quite a common fault on these and in the end they cause the fuse to blow in the fusebox next to the battery. I believe that it is fuse No8 and this controls the coolant fans on some models. I'm not aware of any sort of repair and the flap is used to assist the turning off of the engine and they jam up which causes the light to come on.
The only thing that I can suggest you to try is to remove the unit and then clean out the inside of it removing all the carbon build up. This may help you or it may not.
As for the EGR blanking I tend to say leave it alone if it's not causing you any problems.
I hope this helps and if I can help you further please feel free to ask
There are pros and cons to blanking the EGR valve off. The reason for having it is to help the engine emissions run lower so causing less pollution. It won't cause your car to fail an MOT as the emissions on diesel are done be a smokemeter so it measure how much smoke comes out of the exhaust.
I have seen these blocked off and not cause any issues with the warning light coming on but if you are unlucky and the light comes on there are now people out there that are able to remap the ECU to over come this problem.
There are no laws in place at the moment [preventing you from doing this to your car but there have been various ideas of them changing it in the UK but nothing has ever come from these as of yet.
It won't make your engine run any cooler as it has very little effect on that side of things.