DTC P0404: EGR Valve Open Pintle Position: Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) monitors the Exhaust Gas Recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM. The PCM compares the EGR position sensor with the desired EGR position when the valve is commanded open. If the difference between the EGR position sensor and desired EGR position is more than 10 percent DTC P0404 will set.