Pentair Pool Heater ERR SFS Error Code

Updated 2026-08-29 · review status: manual-verified Last verified: 2026-08-29

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: intermediate

Safety

TBD - must be written per-code before publish

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.

Causes, ranked

  1. 1. Stack flue sensor circuit open or shorted (replace stack flue sensor) common pro-only

    Check:

    Fix:

  2. 2. Corrosion/looseness at J3 and J6 control board connectors occasional diy-ok

    Check:

    Fix:

  3. 3. Heat exchanger coil leaks, liming, soot, or low flow driving flue temp high occasional diy-ok

    Check:

    Fix:

Parts & supplies for Pentair Pool Heater: filters, control boards, sensors, and common replacement parts.

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Sources

  • PoolDial error-code reference (manual-backed) — verified 2026-08-29
  • Pentair MasterTemp/Max-E-Therm Heater Installation & User's Guide (Section 5 Troubleshooting) — verified 2026-08-29