2003 Galant P0403 EGR Valve Circuit Malfunction - Diagnosis and Repair Guide

Good evening, forum members. I'm experiencing a persistent issue with my 2003 Galant V6 3.0L engine, where the check engine light is on due to a P0403 EGR Valve Circuit Malfunction. The vehicle has reached 118,000 miles and I need a reliable repair to pass smog inspection. I've already removed the EGR valve, cleaned carbon deposits, and inspected the electrical connector of the EGR solenoid. I manually tested the solenoid—when activated, it stalled as expected and produced a proper click sound. However, the engine still fails to respond correctly when the EGR system is supposed to activate. My question: Could the issue be that the EGR solenoid isn't functioning properly under actual engine load conditions? Or could there be an electrical or wiring fault between the Powertrain Control Module (PCM) and the solenoid? Any insights, diagnostic steps, or known solutions for this specific P0403 code on a 2003 Galant would be greatly appreciated.