Possible Cause
WARNING: This page is about a different car, the 2018 Nissan Titan XD. However, it is still accessible from the selected car via links, so may be relevant.
- No voltage to DEF control module
- No ground to DEF control module
- Harness and connectors
- Damaged DEF control module
- Blown or missing fuses on battery and ignition inputs to the DEF control module