Dash light on, code 400 or EGR

Hi Bob, my name is Alex and I will be helping you today. Yes, your EGR can be cleaned. Use brake/card cleaner and get where the EGR pipe connects to the EGR valve and the EGR valve connects to the throttle body. There is a EGR vacuum regulator that when commanded by the PCM/ECU opens and allows vacuum to reach the EGR valve, opening it and allowing exhaust gas to enter your throttle body and be reburned in the engines combustion process. Here is a helpful link and a few images for you: https://www.2carpros.com/articles/how-emission-control-systems-work