Diagnosis
E2 on Santa Fe units is almost universally a "high pressure" or "condenser temperature" error. It means the system on the hot side (condenser) is getting too hot, often because the coil is dirty or airflow is restricted.
How to Fix It
The first and most common fix is cleaning. Unplug the unit. Remove the front grille and clean the evaporator coil as described in other answers. But for E2, you also need to check the condenser coil, which is usually on the back or sides of the unit. You may need to remove outer panels to access it. Vacuum any dust/debris from it carefully. Also, make sure there's at least 12-18 inches of clear space on ALL sides of the dehumidifier for proper airflow.
If That Didn't Work
After cleaning and ensuring good airflow, unplug the unit for 30 minutes to let the error clear. If E2 comes back quickly, there could be a deeper issue like a failing fan motor (not moving enough air), a stuck reversing valve (on models that have them for defrost), or a refrigerant overcharge. These require a technician.
Heads Up
Don't just ignore an E2 code and keep resetting it. Running with high pressure can damage the compressor, which is the most expensive part to replace.