2011 Chrysler Grand Voyager 3.8L Engine P0406 OBD2 Code: What It Means and How to Fix It Yourself

My 2011 Chrysler Grand Voyager (3.8L engine, 179 hp) recently triggered the check engine light in my country, which corresponds to the OBD2 fault code P0406 — Exhaust Gas Recirculation (EGR) Sensor A Circuit High. The vehicle was registered as a 2010 model in Canada, but it's actually a 2011 model in my region. I replaced the EGR valve three months ago, and after that, the issue disappeared. However, the P0406 code has returned recently. I want to understand what this error means and whether I can fix it myself without needing professional help. Any advice or troubleshooting steps would be greatly appreciated.