How to Fix / Troubleshooting

Safety: Turn off the unit and isolate power before cleaning or inspection.

Clean filters: Open the front panel of the indoor unit and remove the air filters. Wash with mild detergent and water, dry completely, and reinstall.
Check airflow: Ensure all supply louvers are open and return air is not blocked by furniture or curtains.
Inspect coil for ice: With the cover open, look at the evaporator coil. If iced over, leave the unit off with the front panel open until all ice melts (this may take several hours).
Test fan speed: After thawing, run the unit and cycle through fan speeds. If airflow remains weak, the indoor fan motor or capacitor may be failing.
Monitor operation: If E2 recurs quickly, there may be a refrigerant issue or a faulty coil sensor. Do not attempt to add refrigerant yourself; contact a Vaillant technician for leak detection and charge verification.

E2 error, unit stops and may show signs of evaporator icing or very low airflow

Possible Causes