DTC P0404: EGR Valve Open Pintle Position: Description
WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
Powertrain Control Module (PCM) monitors Exhaust Gas Recirculation (EGR) valve pintle position input to ensure valve responds properly to commands from PCM. PCM compares EGR position sensor with desired EGR position when valve is commanded open. DTC P0404 will set if difference between EGR position sensor and desired EGR position is more than 10 percent.