Pentair Pentair UltraTemp Heat Pump Pool Heater E04 Error Fix: High Pressure Switch Tripped

Error code E04 on the Pentair Pentair UltraTemp Heat Pump Pool Heater means: High Pressure Switch Tripped. The refrigerant high pressure switch has opened, indicating excessive pressure on the discharge side of the compressor. Common causes include a dirty or blocked evaporator coil (obstructed by leaves, debris, or cottonwood), restricted water flow through the heat exchanger (dirty pool filter), refrigerant overcharge, or a malfunctioning reversing valve stuck in the wrong position. Clean the evaporator coil with a garden hose (spray from inside out). Check and clean the pool filter. Verify adequate water flow through the heat pump. The high pressure switch may need to be manually reset.

The most successful fix is "Test and Replace Faulty Pressure Switch" (medium difficulty, ~45 minutes). Estimated DIY cost: $10-$20. 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 ("Test and Replace Faulty Pressure Switch") is rated medium difficulty and takes about 45 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Needle nose pliers.

DIY cost: $10-$20. Professional repair typically costs $150-$250. 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), E05 (Low Pressure Switch Tripped), and 3 more.

Error code E04 also appears on 3 other Pentair models: Pentair IntelliFlo VSF Variable Speed Pool Pump, Pentair IntelliFlo3 VSF Variable Speed Pool Pump, 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.