Pentair Pentair UltraTemp Heat Pump Pool Heater E05 Error Fix: Low Pressure Switch Tripped

Error code E05 on the Pentair Pentair UltraTemp Heat Pump Pool Heater means: Low Pressure Switch Tripped. The refrigerant low pressure switch has opened, indicating abnormally low pressure on the suction side. Common causes include a refrigerant leak (losing charge), operating in ambient temperatures below the heat pump minimum rating (typically 45-50 degrees F for pool heat pumps), a blocked or iced evaporator coil, or a restricted metering device (expansion valve or capillary tube). If the coil is iced, allow it to fully defrost before restarting. Check for refrigerant leaks. Professional refrigerant service is required for charge correction.

The most successful fix is "Check Refrigerant Charge and Repair Leak" (hard difficulty, ~90 minutes). This fix costs nothing. HomeMD has 2 community-ranked fixes for this error.

This error is rated critical severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Check Refrigerant Charge and Repair Leak") is rated hard difficulty and takes about 90 minutes. Tools needed: Electronic refrigerant leak detector, Manifold gauge set, Vacuum pump, Brazing torch.

DIY cost: $0. Professional repair typically costs $300-$600. Many homeowners save money by trying the top-ranked community fix first.

The Pentair Pentair UltraTemp Heat Pump Pool Heater has 8 other known error codes, including: dF (Defrost Mode), E01 (Water Temperature Sensor Fault), E02 (Coil Temperature Sensor Fault), E03 (Ambient Temperature Sensor Fault), E04 (High Pressure Switch Tripped), and 3 more.

Error code E05 also appears on 1 other Pentair model: Pentair MasterTemp 400,000 BTU Gas Pool/Spa Heater. The fix may vary by model, so check each model's specific page for tailored repair steps.