An EGR (engine gas recirculation) valve is simply there to reduce the emission a slight bit by re-feeding the exhaust gasses into the engine; it won't affect your emissions so much that it fails an MOT, being a 1.0. As for the wiring, it will more than likely show a fault code via displaying the EML on your dash, the engine will still run and a bit smoother if anything due to using a constant streem of clean fuel rather than a mix of used / unused vapour. Elegidly you can see throttle response improvement; but using a blanking plate for the egr port can raise the temperature of the head which in turn if your headgasket isnt up to the job will result in part failure. Hope this helps
