P0404 code - serious?

p0404  P0404 fault code This code refers to the EGR valve and its performance On the code reader it refers to 'A'control circuit Does anybody know What is the P0404 Error Code? The P0404 error code is a specific diagnostic trouble code that signifies a problem with the EGR system's

It shows P0404 which I see is a EGR Valve I was looking around alittle and see this might be covered under some federal emission warranty  EGR code P0404 · When Monitored: Engine running · Set Condition: The EGR flow or valve movement is not what is expected A rationality error

Code P0404 usually indicates that there is a carbon build-up somewhere in the lines, or on other occasions, a bad EGR valve  Explanation of what a P0404 Exhaust Gas Recirculation Circuit Range Performance engine