E3 Low pressure protection / low-pressure sensor fault

What the control is telling you

The system tripped on low refrigerant-side pressure, usually from a blocked system or lost charge. On Ultranixx outdoor units E3 is the low-pressure trip and lower-case e3 means the low-pressure sensor signal is out of range for 30 s.

Applies to: Kinghome KM09HT1DI, KM12HT1DI, KM18HT1DI, KM24HT1DI wall mini-splits; Kinghome KM09HF1DI to KM24HF1DI wall mini-splits (Gree GFH..DA/DB); Kinghome Ultranixx Eco KD24UHO to KD60UHO outdoor units with KD..UHI air handlers; Kinghome Ultranixx cold-climate KU36UHO and KU60UHO outdoor units with KU..UH2I and KD..UHI air handlers

Likely causes

• Low charge or refrigerant leak
• Closed service valve or blocked line
• Blocked indoor filter or duct in cooling, outdoor ambient too low
• Fan not working properly
• Faulty low-pressure switch/sensor or poor plug contact (e3)

Test and repair steps

1. Check for a leak and verify the charge.
2. Open the service valves fully and check for line restrictions.
3. Clean the filter and confirm both fans run normally.
4. Test the low-pressure switch or sensor and its connector; replace if faulty.
5. Replace the control board only if the sensor and wiring are good.

Models that show this code

27 models in Kinghome KM HT1DI, Kinghome KM HF1DI, Kinghome Ultranixx Eco, Kinghome Ultranixx

Other codes on the same units

• C5 Jumper cap missing or wrong
• C8 ODU drive jumper cap error
• E1 High pressure protection / high-pressure sensor fault
• E2 Indoor coil anti-freeze protection
• E4 Compressor discharge temperature too high
• E5 Overcurrent protection
• E6 Indoor/outdoor communication fault
• E8 High temperature resistance (overload) protection