Headlights may automatically dip to their lowest position (a "fail-safe" mode) to prevent blinding other drivers, severely reducing nighttime visibility.
Once the calibration is successful, clear the fault code and restart the vehicle to verify that the headlights perform their "startup dance" (moving up and down) correctly. Nissan B20db-54
Low battery voltage or a recent jump-start can sometimes corrupt the configuration data in the IPDM E/R. Step-by-Step Diagnostic & Repair Headlights may automatically dip to their lowest position
A physical failure of the height sensor (often located on the rear axle) can prevent the system from completing its self-check. Nissan B20db-54
An "Auto Leveling" or "System Error" warning may appear on the dashboard.
Defined as "HEIGHT SENS INITIALIZE NOT DONE" .