Pentair Pentair UltraTemp Heat Pump Pool Heater E09 Error Fix: Anti-Freeze Protection

Error code E09 on the Pentair Pentair UltraTemp Heat Pump Pool Heater means: Anti-Freeze Protection. The anti-freeze protection mode has activated. The heat pump is running the water through the heat exchanger to prevent freeze damage in cold weather. This is a normal protective behavior. If E09 appears as an error (rather than a status indication), the anti-freeze protection attempted to activate but encountered a fault — check the water temperature sensor and verify pump operation.

The most successful fix is "Replace Water Temperature Sensor and Test Pump Function" (medium difficulty, ~45 minutes). Estimated DIY cost: $15-$30. HomeMD has 2 community-ranked fixes for this error.

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

Yes — the top-ranked community fix ("Replace Water Temperature Sensor and Test Pump Function") is rated medium difficulty and takes about 45 minutes. Tools needed: Multimeter, Adjustable wrench, Screwdriver set.

DIY cost: $15-$30. 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), E04 (High Pressure Switch Tripped), and 3 more.

Error code E09 also appears on 2 other Pentair models: Pentair IntelliFlo VSF Variable Speed Pool Pump, Pentair IntelliFlo3 VSF Variable Speed Pool Pump. The fix may vary by model, so check each model's specific page for tailored repair steps.