Pentair Pool Heater Error Codes
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- 126 — Shorted Water Temp Sensor Water temperature sensor circuit is shorted. The sensor is
- E01 — Open Water Temp Sensor Water temperature sensor circuit is open. The control board ca
- E05 — Open Stack Flue Sensor Stack flue sensor circuit is open. The SFS thermistor is disco
- E06 — Shorted Stack Flue Sensor Stack flue sensor circuit is shorted. The SFS thermistor is
- ERR AFS — Air Flow Switch Combustion air flow problem detected during the pre-purge cycle. The
- ERR AGS — Automatic Gas Shutoff The automatic gas safety shutoff device has tripped. This is a
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Safe checks with an external tool or supply
These pages list the check you can do from outside the unit, with an optional external tool or maintenance supply. None of them repair an internal fault.
Other pool-heater references
The same fault families appear across brands:
Related troubleshooting guides
Manufacturer manuals
1 codes
- Pentair 126 error code
Shorted Water Temp Sensor Water temperature sensor circuit is shorted. The sensor is reading near-zero resistance, which the board interprets as an ex…
E codes
- Pentair E01 error code
Open Water Temp Sensor Water temperature sensor circuit is open. The control board cannot read the inlet water temperature and has disabled heater ope… - Pentair E05 error code
Open Stack Flue Sensor Stack flue sensor circuit is open. The SFS thermistor is disconnected or has failed with an open-circuit reading. SFS connector… - Pentair E06 error code
Shorted Stack Flue Sensor Stack flue sensor circuit is shorted. The SFS thermistor is reading near-zero resistance, which the control board interprets… - Pentair ERR AFS error code
Air Flow Switch Combustion air flow problem detected during the pre-purge cycle. The blower vacuum switch did not detect the expected negative pressur… - Pentair ERR AGS error code
Automatic Gas Shutoff The automatic gas safety shutoff device has tripped. This is a critical safety lockout that prevents gas from reaching the burne… - Pentair ERR HLS error code
High Limit Switch Water temperature at or near the heat exchanger outlet reached an unsafe level. The high limit switch opened to protect the equipmen… - Pentair ERR IGN error code
Ignition Failure Heater attempted to light 3 times and failed to establish a flame. Blower runs and igniter fires but no combustion occurs. Gas supply… - Pentair ERR PS error code
Water Pressure Switch Insufficient water flow detected before the ignition sequence begins. The pressure switch did not close, preventing the heater f… - Pentair ERR SFS error code
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 g…
S codes
- Pentair SF error code
Service Heater Accumulated error events reaching a threshold, a board-level fault that does not map to a specific sensor code, a service reminder trig…