I have a 200 honda accord with 275K miles on it. I have replace two EGR valves in the last 4 months. The problem I have is after 15 minutes of driving, the car will stall and I have to wait about a minute and it will start back up. and then 2 minutes later it happens again. I can't believe I had two faulty EGR values installed.
Remember that P0401 indicates the symptom, not the root cause.
Carbon build-up along the exhaust gas recirculation line is quite common (and easy enough to clean out), so something as simple as a clogged EGR pipe could explain what's going on here.
You could replace a thousand EGR valves but if there is something else in the EGR loop that is restricting flow it won't do squat to solve the issue.