Pentair Pool Heater E01 Error Code

Updated 2026-08-30 · review status: manual-verified · reviewed by MiniSplitDecoder Editorial Team Last verified: 2026-08-30

Check your model first

The source record does not specify an exact model family.

Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.

Quick answer

Open Water Temp Sensor Water temperature sensor circuit is open. The control board cannot read the inlet water temperature and has disabled heater operation. Sensor connector disconnected or corroded at the manifold, broken wire in the sensor harness, thermistor element failed open from age or water intrusion. Power-cycle the heater. If E01 persists, inspect the water temp sensor connector on the

Severity: high · DIY difficulty: easy

Safety

Stop at the exterior: power-cycle at the disconnect, clean the filter/basket, and check for obvious water-flow blockage. Pool heaters combine gas piping, 240 V wiring, and (on heat pumps) refrigerant — burner, control-board, and sealed-system work requires a licensed technician. If you smell gas, shut the gas valve and leave the area first.

What E01 means

Open Water Temp Sensor Water temperature sensor circuit is open. The control board cannot read the inlet water temperature and has disabled heater operation. Sensor connector disconnected or corroded at the manifold, broken wire in the sensor harness, thermistor element failed open from age or water intrusion. Power-cycle the heater. If E01 persists, inspect the water temp sensor connector on the heater manifold. Measure sensor resistance — should read approximately 10kΩ at 77°F. Infinite resistance confirms an open/failed sensor that must be replaced.

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

  1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

    Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

    Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

  2. 2. Fault persists after a clean reset occasional pro only

    Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

    Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.

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Sources

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