Code P0401, Check Engine?

According to my code reader, a P0401 code indicates an EGR flow problem. "Insufficient exhaust gas recirculation, "A" flow indicated."

My reader displayed also "$0010" in the upper right of the P0401 screen.

Already, I have installed a new EGR valve and cleaned EGR passages with an old speedometer cable attached to a drill driver. The cable emerged with sooty smears, but no large particles were seen.

After cleaning was completed, but before the new EGR valve was RE-installed, I ran the engine briefly until the "Check Engine" light began flashing, and I shut it down. Afterward, no soot particles were found anywhere in the engine bay.

Since I had driven briefly with the new EGR valve installed, and to make sure of my cleaning, I left the new EGR valve soaking in WD40 overnight, then reinstalled the valve.

Next, I cleared old codes from the ECM, and drove about 10 miles. During the drive, the MIL light stayed off until the final three miles, for a total of about seven code-free miles.

The engine still starts, idles and accelerates without hesitation. However, I have limited my driving to avoid possible catalytic converter issues.