Pentair Pool Heater ERR SFS 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

Stack Flue Sensor The stack flue sensor (SFS) circuit is open or the sensor is reading out of the expected operating range. The SFS monitors exhaust gas temperature above the heat exchanger. SFS connector corroded or disconnected, broken wire in the harness between the SFS and control board, SFS thermistor failed open from water intrusion or age.

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 ERR SFS means

Stack Flue Sensor The stack flue sensor (SFS) circuit is open or the sensor is reading out of the expected operating range. The SFS monitors exhaust gas temperature above the heat exchanger. SFS connector corroded or disconnected, broken wire in the harness between the SFS and control board, SFS thermistor failed open from water intrusion or age.

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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