Pentair pool heater error codes must be matched to the heater model, not just the Pentair name. MasterTemp gas heaters and UltraTemp heat pumps use different equipment and diagnostic systems. A message copied from the wrong table can point you toward a component your heater doesn’t have.
Start with the full rating plate and a photograph of the display. Then determine whether the message came from the heater itself or an automation screen. Those two steps establish which manual to use.
Identify the product before searching the code
| Equipment identification | What to obtain | Why the distinction matters |
|---|---|---|
| MasterTemp gas heater | Model, fuel, control display and matching manual | Different controls and model sizes need the applicable documentation |
| MasterTemp 125 | Its specific installation and user guide | Do not assume a larger model’s flow table or procedure applies |
| Max-E-Therm | Its own model and control manual | Shared terminology does not make every specification interchangeable |
| UltraTemp heat pump | Heat pump model and fault table | Refrigeration and defrost conditions need a heat pump diagnostic route |
| ETi or a hybrid system | Exact product designation and manual | Different heating technology and combinations change the fault path |
| Older equipment or an unreadable label | Serial information and manufacturer identification help | Cabinet appearance alone is an unreliable match |
Record the region and fuel designation where shown. Manuals from another market may contain different specifications or installation requirements. A service company should confirm the correct document if the plate is damaged or the control was replaced.
The Pentair control identification guide helps when the unfamiliar name belongs to the controller rather than the heater. ScreenLogic and IntelliCenter are not heater models.
Capture the message exactly where it appears
Keep prefixes such as ERR and distinguish a letter O from a zero. Include any Service System or Service Heater indicator. A general warning light does not uniquely identify an internal fault.
On a compatible connected MasterTemp, the cited guide describes heater alarms appearing at IntelliCenter as well. Record the equipment name assigned to that message. A combined system may contain a pump, heater and other devices with their own alerts.
Older display arrangements may not present the same normal menu or text as the cited LCD guide. Do not remove an energized cover to search for diagnostic lights. Give the model and visible indicators to a qualified technician.
If the heater shows no code, use the no heat decision sequence. A missing error message does not prove that a valid heat request or adequate flow exists.
Verified MasterTemp code examples
These meanings come from the cited MasterTemp guide’s error table. They apply to its covered controls, not every Pentair heater. Match your manual before applying them.
| Display in the cited guide | Detected condition | Initial direction |
|---|---|---|
| ERR PS | Water pressure switch open | Establish pump state and heater flow observations |
| ERR HLS | High temperature limit switch open | Stop repeated trials and investigate heat removal and the safety circuit |
| ERR AFS | Air flow switch open | Qualified blower, airflow and venting diagnosis |
| ERR IGN | Ignition control could not ignite the heater | Qualified ignition and fuel system diagnosis |
| ERR AGS | Automatic gas shutoff temperature protection | Stop use until the cause is assessed |
| ERR SFS | Excessive stack flue temperature | Qualified combustion and heat transfer investigation |
| E05 | Open stack flue sensor circuit | Qualified sensor circuit diagnosis |
| E06 | Shorted stack flue sensor circuit | Qualified sensor circuit diagnosis |
| E01 | Open water temperature sensor circuit | Qualified sensor circuit diagnosis |
| 126 | Shorted water temperature sensor circuit | Qualified sensor circuit diagnosis |
A temperature protection event and a sensor circuit fault are different findings. For example, ERR SFS describes excessive sensed flue temperature, while E05 and E06 identify circuit conditions in this table. Replacing a sensor solely because its name appears in a message can miss the actual fault.
The same caution applies to ERR AFS and ERR PS. Air flow and water pressure belong to different protective systems. Cleaning the pool filter cannot establish that the combustion air path is correct.
Follow the water route for ERR PS
Confirm normal water level, pump prime and the documented heating configuration. Compare filter pressure at the same pump speed and valve setting as its clean baseline. Note a change that coincides with a pump program or pool/spa transition.
The MasterTemp pressure switch guide explains the limits of those observations. Strong returns do not measure the heater branch’s flow. Neither does an RPM number copied from another installation.
Never bridge or adjust a safety switch simply to clear the message. An open input can reflect inadequate flow, the sensing arrangement or an electrical fault. Qualified testing must distinguish them.
Use the event order for ignition and temperature faults
Record whether the fault appeared before heating, after a brief start or after several minutes. Note the requested temperature, displayed temperature and pump state. The shutdown timing record makes these observations easier to compare.
A blower running is not proof that the burner established flame. A heater starting is not proof it can remove heat safely throughout the cycle. Avoid describing either event more confidently than the normal displays support.
Gas odor, soot, steam, banging or burning smells require stopping routine checks. If gas is suspected, leave the area and contact the gas supplier or emergency service from safety. Do not operate electrical switches nearby or repeatedly attempt ignition.
Remote control status is not automatically a fault
On the connected MasterTemp covered by the cited guide, RS485 Control can indicate normal digital control by IntelliCenter. Local controls may be inactive in that state. It does not by itself mean the heater board has failed.
Compare the heat request at the controller with the status at the heater. If local operation works but remote operation does not, use the automation demand checks. Do not substitute a remote mode from another model or connection type.
A phone being offline is also different from an internal heater alarm. Check the outdoor panel before reinstalling software or resetting equipment. Keep the device identities with every screenshot.
Why there is no single reset sequence here
The cited code table uses different clearing conditions for different faults. Some conditions clear when the required input returns; others require a specified action after correction. A generic breaker reset is not a repair procedure.
Follow the exact owner manual only after addressing the cause. Stop repeated resets if the same condition returns. Do not reset an overheating or combustion fault merely to obtain more heating time.
For service, provide the full heater model, manual revision if known, original message and operating sequence. Include any recent controller replacement, plumbing change or fuel work. The correct model and sequence are more useful than a guessed part number.
