MasterTemp® Heater Troubleshooting Guide
Fix Pentair MasterTemp heater fault codes: ERR PS, ERR HLS, ERR AFS, ERR IGN, ERR AGS, ERR SFS, E01, E05, E06, and code 126. Official guide for pressure switch, ignition, and sensor faults.
Common Heater Problems This Guide Covers
A pool technician should open this document when a Pentair MasterTemp heater is displaying an error code on the control panel, failing to ignite, cycling off unexpectedly, or exhibiting abnormal operation..
What it helps you resolve
- MasterTemp displaying ERR PS (water pressure switch open)
- MasterTemp displaying ERR HLS (high temperature limit switch open)
- MasterTemp displaying ERR AFS (air flow switch open)
- MasterTemp displaying ERR IGN (ignition control module fault)
- MasterTemp displaying ERR AGS (automatic gas shutoff)
- MasterTemp displaying ERR SFS (excessive stack flue temperature)
- MasterTemp displaying E01 (open water temperature sensor)
- MasterTemp displaying E05 (open stack flue sensor)
- MasterTemp displaying E06 (shorted stack flue sensor)
- MasterTemp displaying code 126 (shorted water temperature sensor)
- Heater not heating pool water
- Heater igniting then shutting off
When not to use
This document is not for initial heater installation, routine preventative maintenance when no fault is present, or for non-Pentair heater models.
Fault codes covered
Quick diagnosis
Start with the error code on the display. ERR PS and ERR AFS clear automatically once water flow or airflow is restored. ERR IGN and E01 require pressing the HEATER OFF button to reset. ERR AGS and ERR SFS disable the front panel and require a power cycle. For sensor codes E05, E06, and 126, use the wiring diagrams on pages 53-54 before replacing any component.
Qualified personnel only. Opening electrical panels, control boards, or equipment enclosures involves dangerous voltages and should only be performed by licensed pool or electrical technicians. Unauthorized service may void your manufacturer warranty. If unsure, contact a qualified professional.
Still seeing issues with your MasterTemp Heater Troubleshooting Guide?
Our certified technicians know every fault code in this document, including ERR PS, ERR HLS, ERR AFS, and can diagnose your Pentair heater in person across the Oak Island area.
Request ServicePentair Heater FAQs
What does ERR PS mean on a Pentair MasterTemp heater?
ERR PS means the water pressure switch is open, indicating no water flow through the heater. Once flow is established the error clears and normal operation resumes. If flow is present and ERR PS persists, inspect the pressure switch wiring and switch contacts.
How do I clear an ERR IGN error on my MasterTemp?
ERR IGN means the ignition control module was unable to ignite the heater. Press the HEATER OFF button to clear the fault, then diagnose the ignition sequence (gas supply, igniter, flame sensor) before attempting to restart.
Why does my MasterTemp show ERR AGS and why won't the buttons work?
ERR AGS (automatic gas shutoff) fires when water temperature after the second pass through the heat exchanger exceeds 140 degrees F. The front panel buttons are disabled as a safety lockout. To reset, cycle power to the heater. Resolve the root flow or temperature condition before restarting.
What is the difference between ERR SFS and ERR HLS on the MasterTemp?
ERR HLS (high temperature limit switch open) means the water temperature after the first heat exchanger pass exceeded 135 degrees F; it clears automatically when temperature drops below that threshold. ERR SFS (stack flue sensor) means the stack flue temperature exceeded 480 degrees F; it requires a power cycle to reset and indicates a more serious combustion or airflow problem.
How do I diagnose MasterTemp sensor error codes E01, E05, E06, and 126?
E01 is an open water temperature sensor circuit; press HEATER OFF to reset. E05 is an open stack flue sensor and E06 is a shorted stack flue sensor; both require following the wiring diagram on page 54. Code 126 is a shorted water temperature sensor; follow the diagram on page 53. Measure sensor resistance against specification before replacing any part.