2. Detect Malfunctioning Part

WARNING: This page is about a different car, the 2004 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

Check the following.

Harness connectors E22, F35
IPDM E/R harness connector E122
Harness for open or short between EGR volume control valve and IPDM E/R
Harness for open or short between EGR volume control valve and ECM
1. Repair harness or connectors.